diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 41b6450a0a79..e393cfec1bab 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -86,14 +86,6 @@ repos:
         language: python
         files: ^executable_semantics/syntax/parser.ypp$
         pass_filenames: false
-      - id: executable-semantics-tests
-        name: Update list of executable_semantics tests
-        description: Updates executable_semantics/test_list.bzl
-        entry: executable_semantics/tests.py
-        language: python
-        files: ^executable_semantics/(test_list.bzl|testdata/.*\.carbon)$
-        pass_filenames: false
-        args: ['--update_list', '--use_git_ls_files']
       - id: proposal-list
         name: Update list of proposals
         description: Updates the list of proposals in proposals/README.md
diff --git a/bazel/testing/BUILD b/bazel/testing/BUILD
index 79f78bf76308..097d80dde97f 100644
--- a/bazel/testing/BUILD
+++ b/bazel/testing/BUILD
@@ -2,4 +2,4 @@
 # Exceptions. See /LICENSE for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-exports_files(["golden_test.py"])
+exports_files(["lit_test.py"])
diff --git a/bazel/testing/golden_test.bzl b/bazel/testing/golden_test.bzl
deleted file mode 100644
index 0d70c3ec80a9..000000000000
--- a/bazel/testing/golden_test.bzl
+++ /dev/null
@@ -1,33 +0,0 @@
-# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-# Exceptions. See /LICENSE for license information.
-# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-"""Rule for a golden test."""
-
-def golden_test(name, golden, cmd, data, env = None, golden_is_subset = False, **kwargs):
-    """Compares two files. Passes if they are identical.
-
-    Args:
-      name: Name of the build rule.
-      cmd: The command whose output is being tested.
-      golden: The golden file to be compared against the command output.
-      data: Data files.
-      env: Optional environment.
-      golden_is_subset: Set to True if the golden file should be a subset of
-        command output.
-      **kwargs: Any additional parameters for the generated py_test.
-    """
-    args = ["$(location %s)" % golden, cmd]
-    if not env:
-        env = {}
-    if golden_is_subset:
-        args.append("--golden_is_subset")
-    native.py_test(
-        name = name,
-        srcs = ["//bazel/testing:golden_test.py"],
-        main = "//bazel/testing:golden_test.py",
-        args = args,
-        data = [golden] + data,
-        env = env,
-        **kwargs
-    )
diff --git a/bazel/testing/golden_test.py b/bazel/testing/golden_test.py
deleted file mode 100644
index a3fd3d796db0..000000000000
--- a/bazel/testing/golden_test.py
+++ /dev/null
@@ -1,147 +0,0 @@
-#!/usr/bin/env python3
-
-"""Compare a command's output against an expected "golden" output file.
-
-Usage:
-
-golden_test.py <golden path> <command> [--update]
-
-<golden path> is the path to the golden file, and <command> is
-the command to run, including any arguments. If --update is specified,
-the command will be run and its output stored in the golden file.
-Otherwise, the command will be run and its output compared against
-the contents of the golden file.
-
-For these purposes, the command's output consists of the interleaved
-contents of stdout and stderr, as well as the command's exit code. Thus,
-golden tests can provide coverage of cases where the command is expected
-to fail, as well as cases where it's expected to succeed.
-
-This script is designed to be run by a `golden_test` Bazel rule,
-and may not work when run outside that context.
-"""
-
-__copyright__ = """
-Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-Exceptions. See /LICENSE for license information.
-SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-"""
-
-import argparse
-import difflib
-import os
-import subprocess
-import sys
-
-
-_ERROR_MESSAGE = """When running under:
-  {dir}
-the golden contents of:
-  {golden_path}
-do not match generated output of:
-  {subject_cmd_args}
-"""
-
-_UPDATE_MESSAGE = """To update the golden file, run the following:
-
-  bazel run {test_target} -- --update
-"""
-
-
-def _parse_args():
-    """Parses command line arguments, returning the result."""
-    arg_parser = argparse.ArgumentParser(description=__doc__)
-    arg_parser.add_argument("golden_path", help="The path to the golden file.")
-    arg_parser.add_argument(
-        "subject_command", help="The command line to compare output with."
-    )
-    arg_parser.add_argument(
-        "--golden_is_subset",
-        action="store_true",
-        help="Indicates that the golden file will be a subset of output, "
-        "rather than full output.",
-    )
-    arg_parser.add_argument(
-        "--update",
-        action="store_true",
-        help="Whether to update the golden file.",
-    )
-    return arg_parser.parse_args()
-
-
-def _get_subject_output(args):
-    """Returns output from the subject command."""
-    subject_cmd = subprocess.run(
-        args=args.subject_command.split(),
-        stdout=subprocess.PIPE,  # Capture stdout as a string
-        stderr=subprocess.STDOUT,  # Send stderr to the same place as stdout
-        universal_newlines=True,
-    )
-
-    subject = subject_cmd.stdout
-    if subject_cmd.returncode != 0:
-        subject += "EXIT CODE: {0}\n".format(subject_cmd.returncode)
-
-    return subject
-
-
-def _check_diff(args, subject):
-    """Prints and checks the diff. Returns the appropriate exit code."""
-    subject_lines = subject.splitlines(keepends=True)
-    with open(args.golden_path) as golden:
-        golden_lines = list(golden.readlines())
-    if args.golden_is_subset:
-        golden_set = frozenset(golden_lines)
-        subject_lines = [line for line in subject_lines if line in golden_set]
-    context_diff = list(
-        difflib.context_diff(
-            subject_lines, golden_lines, fromfile="subject", tofile="golden"
-        )
-    )
-    if context_diff:
-        if args.golden_is_subset:
-            # Print subject output for context, because it may be useful in
-            # debugging.
-            print("=" * 80)
-            print("Subject output (including ignored lines)")
-            print("=" * 80)
-            print(subject)
-        print("=" * 80)
-        print("Output diff")
-        print("=" * 80)
-        sys.stdout.writelines(context_diff)
-        print("=" * 80)
-        print(
-            _ERROR_MESSAGE.format(
-                dir=os.getenv("TEST_SRCDIR"),
-                golden_path=args.golden_path,
-                subject_cmd_args=args.subject_command,
-            )
-        )
-        if not args.golden_is_subset:
-            print(
-                _UPDATE_MESSAGE.format(
-                    test_target=os.getenv("TEST_TARGET"),
-                )
-            )
-
-        return 1
-    else:
-        print("PASS")
-        return 0
-
-
-def main():
-    args = _parse_args()
-    subject = _get_subject_output(args)
-
-    if args.update:
-        with open(args.golden_path, "w") as golden:
-            golden.write(subject)
-            return 0
-
-    return _check_diff(args, subject)
-
-
-if __name__ == "__main__":
-    sys.exit(main())
diff --git a/bazel/testing/lit_test.bzl b/bazel/testing/lit_test.bzl
new file mode 100644
index 000000000000..cc3c5b973f4e
--- /dev/null
+++ b/bazel/testing/lit_test.bzl
@@ -0,0 +1,38 @@
+# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+# Exceptions. See /LICENSE for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+"""Rule for a lit test."""
+
+def lit_test(name, test_dir, tools = None, **kwargs):
+    """Runs `lit` on test_dir.
+
+    `lit` reference:
+      https://llvm.org/docs/CommandGuide/lit.html
+
+    To pass flags to `lit`, use `--test_arg`. For example:
+      bazel test :lit_test --test_arg=-v
+      bazel test :lit_test --test_arg=--filter=REGEXP
+
+    Args:
+      name: Name of the build rule.
+      test_dir: The directory with the lit tests.
+      tools: An optional list of tools to provide to the tests. These will be
+        aliased for execution.
+      **kwargs: Any additional parameters for the generated py_test.
+    """
+    if not tools:
+        tools = []
+    tools += [
+        "@llvm-project//llvm:lit",
+        "@llvm-project//llvm:not",
+        "@llvm-project//llvm:FileCheck",
+    ]
+    native.py_test(
+        name = name,
+        srcs = ["//bazel/testing:lit_test.py"],
+        main = "//bazel/testing:lit_test.py",
+        data = tools + native.glob([test_dir + "/**"]),
+        args = ["--tool=%s" % t for t in tools] + [test_dir, "--"],
+        **kwargs
+    )
diff --git a/bazel/testing/lit_test.py b/bazel/testing/lit_test.py
new file mode 100644
index 000000000000..44e2851de859
--- /dev/null
+++ b/bazel/testing/lit_test.py
@@ -0,0 +1,93 @@
+"""Runs `lit` for testing."""
+
+__copyright__ = """
+Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+Exceptions. See /LICENSE for license information.
+SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+"""
+
+import argparse
+import os
+import subprocess
+
+_PASSTHROUGH_FLAGS = ["filter", "filter-out"]
+
+
+def _parse_args():
+    """Parses command line arguments, returning the result."""
+    arg_parser = argparse.ArgumentParser(description=__doc__)
+    arg_parser.add_argument(
+        "test_dir", help="The directory containing tests to run."
+    )
+    arg_parser.add_argument(
+        "lit_args", nargs="*", help="Arguments to pass through to lit."
+    )
+    arg_parser.add_argument(
+        "--tool", action="append", help="A tool to add to the PATH."
+    )
+    return arg_parser.parse_args()
+
+
+def _normalize(relative_base, target):
+    """Given a target, normalizes it to a relative path."""
+    assert target
+    if target.startswith(":"):
+        # Local target; :foo -> my/dir/foo
+        return os.path.join(relative_base, target[1:])
+    elif target[0].isalpha():
+        # Local target; foo -> my/dir/foo
+        return os.path.join(relative_base, target)
+
+    if ":" in target:
+        # Specified target; //foo:bar -> //foo/bar
+        target = target.replace(":", "/")
+    else:
+        # Default target; //foo -> //foo/foo
+        target = os.path.join(target, os.path.basename(target))
+
+    if target.startswith("@"):
+        return os.path.join("external/", target[1:])
+    elif target.startswith("//"):
+        return target[2:]
+    else:
+        raise ValueError("Unhandled target path: %s" % target)
+
+
+def main():
+    parsed_args = _parse_args()
+
+    # A symlink directory is added to the PATH so that commands like `lit` and
+    # `not` can use the versions in the path.
+    symlink_dir = os.environ["TEST_TMPDIR"]
+
+    # Create symlinks to all the tools.
+    bin_dir = os.getcwd()
+    relative_base = os.path.dirname(_normalize("", os.environ["TEST_TARGET"]))
+    for tool in parsed_args.tool:
+        tool_path = _normalize(relative_base, tool)
+        symlink_loc = os.path.join(symlink_dir, os.path.basename(tool_path))
+        symlinked_file = os.path.join(bin_dir, tool_path)
+        if not os.path.exists(symlinked_file):
+            raise ValueError("Missing file: %s" % symlinked_file)
+        os.symlink(symlinked_file, symlink_loc)
+
+    # Figure out the actual path for the test_dir.
+    test_dir = os.path.join(
+        bin_dir, _normalize(relative_base, parsed_args.test_dir)
+    )
+
+    args = [
+        os.path.join(symlink_dir, "lit"),
+        "--path=%s" % symlink_dir,
+        test_dir,
+    ]
+
+    # Run lit.
+    p = subprocess.run(args=args + parsed_args.lit_args)
+    # Do this instead of check_call to hide stack traces.
+    if p.returncode != 0:
+        exit("lit failed, exit code %d" % p.returncode)
+
+
+if __name__ == "__main__":
+    exit(main())
diff --git a/executable_semantics/BUILD b/executable_semantics/BUILD
index 5a17f7d0e203..c69935958890 100644
--- a/executable_semantics/BUILD
+++ b/executable_semantics/BUILD
@@ -2,8 +2,7 @@
 # Exceptions. See /LICENSE for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-load("//bazel/testing:golden_test.bzl", "golden_test")
-load("test_list.bzl", "TEST_LIST")
+load("//bazel/testing:lit_test.bzl", "lit_test")
 
 cc_binary(
     name = "executable_semantics",
@@ -16,38 +15,8 @@ cc_binary(
     ],
 )
 
-[golden_test(
-    name = "%s_test" % e,
-    cmd = "'$(location executable_semantics) $(location testdata/%s.carbon)'" % e,
-    data = [
-        ":executable_semantics",
-        "testdata/%s.carbon" % e,
-    ],
-    golden = "testdata/%s.golden" % e,
-) for e in TEST_LIST]
-
-# Convenience suite for running golden tests.
-test_suite(
-    name = "golden_tests",
-    tests = [":%s_test" % e for e in TEST_LIST],
-)
-
-# Test --trace by expecting golden output to be a *subset* of trace output. Note
-# the normal test must be used to update golden files.
-[golden_test(
-    name = "%s_trace_test" % e,
-    cmd = "'$(location executable_semantics) --trace " +
-          "$(location testdata/%s.carbon)'" % e,
-    data = [
-        ":executable_semantics",
-        "testdata/%s.carbon" % e,
-    ],
-    golden = "testdata/%s.golden" % e,
-    golden_is_subset = True,
-) for e in TEST_LIST]
-
-# Convenience suite for running trace tests.
-test_suite(
-    name = "trace_tests",
-    tests = [":%s_trace_test" % e for e in TEST_LIST],
+lit_test(
+    name = "executable_semantics_lit_test",
+    test_dir = "testdata",
+    tools = [":executable_semantics"],
 )
diff --git a/executable_semantics/test_list.bzl b/executable_semantics/test_list.bzl
deleted file mode 100644
index 3d0cfbb701b7..000000000000
--- a/executable_semantics/test_list.bzl
+++ /dev/null
@@ -1,115 +0,0 @@
-# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-# Exceptions. See /LICENSE for license information.
-# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-"""Auto-generated list of tests. Run `./tests.py --update_list` to update."""
-
-TEST_LIST = [
-    "assignment_copy1",
-    "assignment_copy2",
-    "block1",
-    "block2",
-    "break1",
-    "choice1",
-    "class1",
-    "class2",
-    "class3",
-    "class_field_access_mismatch",
-    "class_field_mismatch",
-    "class_field_missing",
-    "continue1",
-    "experimental_continuation1",
-    "experimental_continuation2",
-    "experimental_continuation3",
-    "experimental_continuation4",
-    "experimental_continuation5",
-    "experimental_continuation6",
-    "experimental_continuation7",
-    "experimental_continuation9",
-    "fun1",
-    "fun2",
-    "fun3",
-    "fun4",
-    "fun5",
-    "fun6_fail_type",
-    "fun_named_params",
-    "fun_named_params2",
-    "fun_recur",
-    "funptr1",
-    "generic_function1",
-    "generic_function2",
-    "generic_function3",
-    "generic_function_apply",
-    "generic_function_fail1",
-    "generic_function_fail2",
-    "generic_function_fail3",
-    "generic_function_swap",
-    "generic_function_tuple_map",
-    "global_variable1",
-    "global_variable2",
-    "global_variable3",
-    "global_variable4",
-    "global_variable5",
-    "global_variable6",
-    "global_variable7",
-    "global_variable8",
-    "if_else",
-    "if_else_if",
-    "if_else_if_else",
-    "if_false",
-    "if_nesting",
-    "if_true",
-    "ignored_parameter",
-    "import_late",
-    "import_nonexistent_library",
-    "import_nonexistent_package",
-    "invalid_char",
-    "match_any_int",
-    "match_int",
-    "match_int_default",
-    "match_placeholder",
-    "next",
-    "no_match",
-    "package_library",
-    "package_missing",
-    "pattern_init",
-    "pattern_variable_fail",
-    "placeholder_variable",
-    "print1",
-    "record1",
-    "return_auto",
-    "return_empty_explicit",
-    "return_empty_explicit_fail",
-    "return_empty_implicit1",
-    "return_empty_implicit2",
-    "return_empty_implicit_fail1",
-    "return_empty_implicit_fail2",
-    "star",
-    "string1",
-    "string2",
-    "string3",
-    "string_fail1",
-    "string_fail2",
-    "string_fail3",
-    "string_fail4",
-    "string_fail5",
-    "string_fail6",
-    "tuple1",
-    "tuple2",
-    "tuple3",
-    "tuple4",
-    "tuple5",
-    "tuple_assign",
-    "tuple_equality",
-    "tuple_equality2",
-    "tuple_equality3",
-    "tuple_match",
-    "tuple_match2",
-    "tuple_match3",
-    "type_compute",
-    "type_compute2",
-    "type_compute3",
-    "type_match",
-    "while1",
-    "zero",
-]
diff --git a/executable_semantics/testdata/assignment_copy1.carbon b/executable_semantics/testdata/assignment_copy1.carbon
index 2ce230b44d70..1603da5569e6 100644
--- a/executable_semantics/testdata/assignment_copy1.carbon
+++ b/executable_semantics/testdata/assignment_copy1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/assignment_copy1.golden b/executable_semantics/testdata/assignment_copy1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/assignment_copy1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/assignment_copy2.carbon b/executable_semantics/testdata/assignment_copy2.carbon
index ea47574404db..f5ca262aa721 100644
--- a/executable_semantics/testdata/assignment_copy2.carbon
+++ b/executable_semantics/testdata/assignment_copy2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/assignment_copy2.golden b/executable_semantics/testdata/assignment_copy2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/assignment_copy2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/block1.carbon b/executable_semantics/testdata/block1.carbon
index 27014dc98af4..cbe9e1ec41a3 100644
--- a/executable_semantics/testdata/block1.carbon
+++ b/executable_semantics/testdata/block1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/block1.golden b/executable_semantics/testdata/block1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/block1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/block2.carbon b/executable_semantics/testdata/block2.carbon
index b3651b091dd9..5d4622d3f34a 100644
--- a/executable_semantics/testdata/block2.carbon
+++ b/executable_semantics/testdata/block2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/block2.golden b/executable_semantics/testdata/block2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/block2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/break1.carbon b/executable_semantics/testdata/break1.carbon
index 419179e1146e..cde9fb3be9eb 100644
--- a/executable_semantics/testdata/break1.carbon
+++ b/executable_semantics/testdata/break1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/break1.golden b/executable_semantics/testdata/break1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/break1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/choice1.carbon b/executable_semantics/testdata/choice1.carbon
index ca12a8a1b47a..05dd56bcbf1e 100644
--- a/executable_semantics/testdata/choice1.carbon
+++ b/executable_semantics/testdata/choice1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/choice1.golden b/executable_semantics/testdata/choice1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/choice1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/class1.carbon b/executable_semantics/testdata/class1.carbon
index 86ca039a0436..d3574e2ec11b 100644
--- a/executable_semantics/testdata/class1.carbon
+++ b/executable_semantics/testdata/class1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/class1.golden b/executable_semantics/testdata/class1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/class1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/class2.carbon b/executable_semantics/testdata/class2.carbon
index 838a9c65b978..0b0f0abc3aec 100644
--- a/executable_semantics/testdata/class2.carbon
+++ b/executable_semantics/testdata/class2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/class2.golden b/executable_semantics/testdata/class2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/class2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/class3.carbon b/executable_semantics/testdata/class3.carbon
index bf5a8ae7ba8c..7ceb047e3ee4 100644
--- a/executable_semantics/testdata/class3.carbon
+++ b/executable_semantics/testdata/class3.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/class3.golden b/executable_semantics/testdata/class3.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/class3.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/class_field_access_mismatch.carbon b/executable_semantics/testdata/class_field_access_mismatch.carbon
index 5283b9a2fdfc..7c266a31b0aa 100644
--- a/executable_semantics/testdata/class_field_access_mismatch.carbon
+++ b/executable_semantics/testdata/class_field_access_mismatch.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/class_field_access_mismatch.carbon:21: class Point does not have a field named z
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/class_field_access_mismatch.golden b/executable_semantics/testdata/class_field_access_mismatch.golden
deleted file mode 100644
index 4e96bed3d862..000000000000
--- a/executable_semantics/testdata/class_field_access_mismatch.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/class_field_access_mismatch.carbon:13: class Point does not have a field named z
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/class_field_mismatch.carbon b/executable_semantics/testdata/class_field_mismatch.carbon
index c8dc5930163b..629d050b3e8c 100644
--- a/executable_semantics/testdata/class_field_mismatch.carbon
+++ b/executable_semantics/testdata/class_field_mismatch.carbon
@@ -1,6 +1,16 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/class_field_mismatch.carbon:23: type error in call
+// CHECK: expected: (x = i32, y = i32)
+// CHECK: actual: (x = i32, z = i32)
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/class_field_mismatch.golden b/executable_semantics/testdata/class_field_mismatch.golden
deleted file mode 100644
index 66e557f97660..000000000000
--- a/executable_semantics/testdata/class_field_mismatch.golden
+++ /dev/null
@@ -1,4 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/class_field_mismatch.carbon:13: type error in call
-expected: (x = i32, y = i32)
-actual: (x = i32, z = i32)
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/class_field_missing.carbon b/executable_semantics/testdata/class_field_missing.carbon
index 3fc71fc0b61f..25d3e3f4694d 100644
--- a/executable_semantics/testdata/class_field_missing.carbon
+++ b/executable_semantics/testdata/class_field_missing.carbon
@@ -1,6 +1,16 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/class_field_missing.carbon:23: type error in call
+// CHECK: expected: (x = i32, y = i32)
+// CHECK: actual: (x = i32)
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/class_field_missing.golden b/executable_semantics/testdata/class_field_missing.golden
deleted file mode 100644
index ab9861632476..000000000000
--- a/executable_semantics/testdata/class_field_missing.golden
+++ /dev/null
@@ -1,4 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/class_field_missing.carbon:13: type error in call
-expected: (x = i32, y = i32)
-actual: (x = i32)
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/continue1.carbon b/executable_semantics/testdata/continue1.carbon
index 75f6611d232b..968c03c28d6f 100644
--- a/executable_semantics/testdata/continue1.carbon
+++ b/executable_semantics/testdata/continue1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/continue1.golden b/executable_semantics/testdata/continue1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/continue1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/experimental_continuation1.carbon b/executable_semantics/testdata/experimental_continuation1.carbon
index 179814c5d3a5..ee0e8a3e00c7 100644
--- a/executable_semantics/testdata/experimental_continuation1.carbon
+++ b/executable_semantics/testdata/experimental_continuation1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/experimental_continuation1.golden b/executable_semantics/testdata/experimental_continuation1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/experimental_continuation1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/experimental_continuation2.carbon b/executable_semantics/testdata/experimental_continuation2.carbon
index a1a15302ad82..43bd505059bd 100644
--- a/executable_semantics/testdata/experimental_continuation2.carbon
+++ b/executable_semantics/testdata/experimental_continuation2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 1
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/experimental_continuation2.golden b/executable_semantics/testdata/experimental_continuation2.golden
deleted file mode 100644
index 0c204052cb21..000000000000
--- a/executable_semantics/testdata/experimental_continuation2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 1
diff --git a/executable_semantics/testdata/experimental_continuation3.carbon b/executable_semantics/testdata/experimental_continuation3.carbon
index 8d9483681da0..2bdacede6809 100644
--- a/executable_semantics/testdata/experimental_continuation3.carbon
+++ b/executable_semantics/testdata/experimental_continuation3.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 3
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/experimental_continuation3.golden b/executable_semantics/testdata/experimental_continuation3.golden
deleted file mode 100644
index 18860b8659c0..000000000000
--- a/executable_semantics/testdata/experimental_continuation3.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 3
diff --git a/executable_semantics/testdata/experimental_continuation4.carbon b/executable_semantics/testdata/experimental_continuation4.carbon
index 78baab3cfa4c..5399cc8750e7 100644
--- a/executable_semantics/testdata/experimental_continuation4.carbon
+++ b/executable_semantics/testdata/experimental_continuation4.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 3
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/experimental_continuation4.golden b/executable_semantics/testdata/experimental_continuation4.golden
deleted file mode 100644
index 18860b8659c0..000000000000
--- a/executable_semantics/testdata/experimental_continuation4.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 3
diff --git a/executable_semantics/testdata/experimental_continuation5.carbon b/executable_semantics/testdata/experimental_continuation5.carbon
index 07f24745d00b..4043a21d2a86 100644
--- a/executable_semantics/testdata/experimental_continuation5.carbon
+++ b/executable_semantics/testdata/experimental_continuation5.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 3
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/experimental_continuation5.golden b/executable_semantics/testdata/experimental_continuation5.golden
deleted file mode 100644
index 18860b8659c0..000000000000
--- a/executable_semantics/testdata/experimental_continuation5.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 3
diff --git a/executable_semantics/testdata/experimental_continuation6.carbon b/executable_semantics/testdata/experimental_continuation6.carbon
index ecd0b5a9b4fd..9d859baa6838 100644
--- a/executable_semantics/testdata/experimental_continuation6.carbon
+++ b/executable_semantics/testdata/experimental_continuation6.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 10
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/experimental_continuation6.golden b/executable_semantics/testdata/experimental_continuation6.golden
deleted file mode 100644
index 0e0834d8b4da..000000000000
--- a/executable_semantics/testdata/experimental_continuation6.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 10
diff --git a/executable_semantics/testdata/experimental_continuation7.carbon b/executable_semantics/testdata/experimental_continuation7.carbon
index 4c79aecf68ea..2da75da184fc 100644
--- a/executable_semantics/testdata/experimental_continuation7.carbon
+++ b/executable_semantics/testdata/experimental_continuation7.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 3
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/experimental_continuation7.golden b/executable_semantics/testdata/experimental_continuation7.golden
deleted file mode 100644
index 18860b8659c0..000000000000
--- a/executable_semantics/testdata/experimental_continuation7.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 3
diff --git a/executable_semantics/testdata/experimental_continuation9.carbon b/executable_semantics/testdata/experimental_continuation9.carbon
index ab1c6ec35356..2585d872d7d0 100644
--- a/executable_semantics/testdata/experimental_continuation9.carbon
+++ b/executable_semantics/testdata/experimental_continuation9.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: RUNTIME ERROR: {{.*}}/experimental_continuation9.carbon:22: undefined behavior: access to dead value 1
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/experimental_continuation9.golden b/executable_semantics/testdata/experimental_continuation9.golden
deleted file mode 100644
index 6997e4f3914f..000000000000
--- a/executable_semantics/testdata/experimental_continuation9.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-RUNTIME ERROR: executable_semantics/testdata/experimental_continuation9.carbon:14: undefined behavior: access to dead value 1
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/fun1.carbon b/executable_semantics/testdata/fun1.carbon
index 3fbbc11df351..14150b24b6be 100644
--- a/executable_semantics/testdata/fun1.carbon
+++ b/executable_semantics/testdata/fun1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/fun1.golden b/executable_semantics/testdata/fun1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/fun1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/fun2.carbon b/executable_semantics/testdata/fun2.carbon
index 14d05e157256..c789c6f35cf4 100644
--- a/executable_semantics/testdata/fun2.carbon
+++ b/executable_semantics/testdata/fun2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/fun2.golden b/executable_semantics/testdata/fun2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/fun2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/fun3.carbon b/executable_semantics/testdata/fun3.carbon
index 9fa23b4eb8ca..5a013a463cd5 100644
--- a/executable_semantics/testdata/fun3.carbon
+++ b/executable_semantics/testdata/fun3.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/fun3.golden b/executable_semantics/testdata/fun3.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/fun3.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/fun4.carbon b/executable_semantics/testdata/fun4.carbon
index 332c84240b74..bcc64ebc5cee 100644
--- a/executable_semantics/testdata/fun4.carbon
+++ b/executable_semantics/testdata/fun4.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/fun4.golden b/executable_semantics/testdata/fun4.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/fun4.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/fun5.carbon b/executable_semantics/testdata/fun5.carbon
index eced169d666e..233311ce2565 100644
--- a/executable_semantics/testdata/fun5.carbon
+++ b/executable_semantics/testdata/fun5.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/fun5.golden b/executable_semantics/testdata/fun5.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/fun5.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/fun6_fail_type.carbon b/executable_semantics/testdata/fun6_fail_type.carbon
index 22123ee50a71..c9657798ce04 100644
--- a/executable_semantics/testdata/fun6_fail_type.carbon
+++ b/executable_semantics/testdata/fun6_fail_type.carbon
@@ -1,6 +1,16 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/fun6_fail_type.carbon:22: type error in call
+// CHECK: expected: (0 = i32, 1 = i32)
+// CHECK: actual: (0 = (0 = i32, 1 = i32))
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/fun6_fail_type.golden b/executable_semantics/testdata/fun6_fail_type.golden
deleted file mode 100644
index aa9005864c60..000000000000
--- a/executable_semantics/testdata/fun6_fail_type.golden
+++ /dev/null
@@ -1,4 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/fun6_fail_type.carbon:12: type error in call
-expected: (0 = i32, 1 = i32)
-actual: (0 = (0 = i32, 1 = i32))
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/fun_named_params.carbon b/executable_semantics/testdata/fun_named_params.carbon
index f325ddff6eab..5fe6255a8810 100644
--- a/executable_semantics/testdata/fun_named_params.carbon
+++ b/executable_semantics/testdata/fun_named_params.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/fun_named_params.golden b/executable_semantics/testdata/fun_named_params.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/fun_named_params.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/fun_named_params2.carbon b/executable_semantics/testdata/fun_named_params2.carbon
index 41b37a43b01b..888e6f0f4db5 100644
--- a/executable_semantics/testdata/fun_named_params2.carbon
+++ b/executable_semantics/testdata/fun_named_params2.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: PROGRAM ERROR: {{.*}}/fun_named_params2.carbon:15: positional members must come before named members
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/fun_named_params2.golden b/executable_semantics/testdata/fun_named_params2.golden
deleted file mode 100644
index 880c91ad4bc4..000000000000
--- a/executable_semantics/testdata/fun_named_params2.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-PROGRAM ERROR: executable_semantics/testdata/fun_named_params2.carbon:7: positional members must come before named members
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/fun_recur.carbon b/executable_semantics/testdata/fun_recur.carbon
index 2f515e065b60..02d022129083 100644
--- a/executable_semantics/testdata/fun_recur.carbon
+++ b/executable_semantics/testdata/fun_recur.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/fun_recur.golden b/executable_semantics/testdata/fun_recur.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/fun_recur.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/funptr1.carbon b/executable_semantics/testdata/funptr1.carbon
index b1f4b423aaa0..e1179d81191d 100644
--- a/executable_semantics/testdata/funptr1.carbon
+++ b/executable_semantics/testdata/funptr1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/funptr1.golden b/executable_semantics/testdata/funptr1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/funptr1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/generic_function1.carbon b/executable_semantics/testdata/generic_function1.carbon
index a0fbd8b5107c..fccb8277b60e 100644
--- a/executable_semantics/testdata/generic_function1.carbon
+++ b/executable_semantics/testdata/generic_function1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/generic_function1.golden b/executable_semantics/testdata/generic_function1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/generic_function1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/generic_function2.carbon b/executable_semantics/testdata/generic_function2.carbon
index 4c4678079ece..74b43d5409d4 100644
--- a/executable_semantics/testdata/generic_function2.carbon
+++ b/executable_semantics/testdata/generic_function2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/generic_function2.golden b/executable_semantics/testdata/generic_function2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/generic_function2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/generic_function3.carbon b/executable_semantics/testdata/generic_function3.carbon
index b33c02f0f734..d71ef1e0fc01 100644
--- a/executable_semantics/testdata/generic_function3.carbon
+++ b/executable_semantics/testdata/generic_function3.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 1
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/generic_function3.golden b/executable_semantics/testdata/generic_function3.golden
deleted file mode 100644
index 0c204052cb21..000000000000
--- a/executable_semantics/testdata/generic_function3.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 1
diff --git a/executable_semantics/testdata/generic_function_apply.carbon b/executable_semantics/testdata/generic_function_apply.carbon
index b36f8614ca8a..d7e261e1296a 100644
--- a/executable_semantics/testdata/generic_function_apply.carbon
+++ b/executable_semantics/testdata/generic_function_apply.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: -2
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/generic_function_apply.golden b/executable_semantics/testdata/generic_function_apply.golden
deleted file mode 100644
index 49f08b507230..000000000000
--- a/executable_semantics/testdata/generic_function_apply.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: -2
diff --git a/executable_semantics/testdata/generic_function_fail1.carbon b/executable_semantics/testdata/generic_function_fail1.carbon
index e7f48cd91078..8a62cf7d026b 100644
--- a/executable_semantics/testdata/generic_function_fail1.carbon
+++ b/executable_semantics/testdata/generic_function_fail1.carbon
@@ -1,6 +1,16 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/generic_function_fail1.carbon:22: type error in argument deduction
+// CHECK: expected: i32
+// CHECK: actual: Bool
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/generic_function_fail1.golden b/executable_semantics/testdata/generic_function_fail1.golden
deleted file mode 100644
index 949f89c36e98..000000000000
--- a/executable_semantics/testdata/generic_function_fail1.golden
+++ /dev/null
@@ -1,4 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/generic_function_fail1.carbon:12: type error in argument deduction
-expected: i32
-actual: Bool
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/generic_function_fail2.carbon b/executable_semantics/testdata/generic_function_fail2.carbon
index e82b36942148..3321bb8a210a 100644
--- a/executable_semantics/testdata/generic_function_fail2.carbon
+++ b/executable_semantics/testdata/generic_function_fail2.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/generic_function_fail2.carbon:20: could not deduce type argument for type parameter T
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/generic_function_fail2.golden b/executable_semantics/testdata/generic_function_fail2.golden
deleted file mode 100644
index aa238bc0f950..000000000000
--- a/executable_semantics/testdata/generic_function_fail2.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/generic_function_fail2.carbon:12: could not deduce type argument for type parameter T
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/generic_function_fail3.carbon b/executable_semantics/testdata/generic_function_fail3.carbon
index 352f48610b19..d347bd2f195e 100644
--- a/executable_semantics/testdata/generic_function_fail3.carbon
+++ b/executable_semantics/testdata/generic_function_fail3.carbon
@@ -1,6 +1,16 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/generic_function_fail3.carbon:18: type error in addition(1)
+// CHECK: expected: i32
+// CHECK: actual: T
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/generic_function_fail3.golden b/executable_semantics/testdata/generic_function_fail3.golden
deleted file mode 100644
index ec4fa10be89c..000000000000
--- a/executable_semantics/testdata/generic_function_fail3.golden
+++ /dev/null
@@ -1,4 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/generic_function_fail3.carbon:8: type error in addition(1)
-expected: i32
-actual: T
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/generic_function_swap.carbon b/executable_semantics/testdata/generic_function_swap.carbon
index 10ef63101ffd..e6681a55b1dc 100644
--- a/executable_semantics/testdata/generic_function_swap.carbon
+++ b/executable_semantics/testdata/generic_function_swap.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/generic_function_swap.golden b/executable_semantics/testdata/generic_function_swap.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/generic_function_swap.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/generic_function_tuple_map.carbon b/executable_semantics/testdata/generic_function_tuple_map.carbon
index 6fb929ea1b28..30dd7aebbb32 100644
--- a/executable_semantics/testdata/generic_function_tuple_map.carbon
+++ b/executable_semantics/testdata/generic_function_tuple_map.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 1
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/generic_function_tuple_map.golden b/executable_semantics/testdata/generic_function_tuple_map.golden
deleted file mode 100644
index 0c204052cb21..000000000000
--- a/executable_semantics/testdata/generic_function_tuple_map.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 1
diff --git a/executable_semantics/testdata/global_variable1.carbon b/executable_semantics/testdata/global_variable1.carbon
index c00ec72ae422..02f00de0f1ec 100644
--- a/executable_semantics/testdata/global_variable1.carbon
+++ b/executable_semantics/testdata/global_variable1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/global_variable1.golden b/executable_semantics/testdata/global_variable1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/global_variable1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/global_variable2.carbon b/executable_semantics/testdata/global_variable2.carbon
index 61ed5ad9db0f..3858438e39cc 100644
--- a/executable_semantics/testdata/global_variable2.carbon
+++ b/executable_semantics/testdata/global_variable2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/global_variable2.golden b/executable_semantics/testdata/global_variable2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/global_variable2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/global_variable3.carbon b/executable_semantics/testdata/global_variable3.carbon
index 1caf0e0db79c..0fb730d24cf3 100644
--- a/executable_semantics/testdata/global_variable3.carbon
+++ b/executable_semantics/testdata/global_variable3.carbon
@@ -1,6 +1,16 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/global_variable3.carbon:19: type error in initializer of variable
+// CHECK: expected: i32
+// CHECK: actual: Bool
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/global_variable3.golden b/executable_semantics/testdata/global_variable3.golden
deleted file mode 100644
index 1bcf3a8b007d..000000000000
--- a/executable_semantics/testdata/global_variable3.golden
+++ /dev/null
@@ -1,4 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/global_variable3.carbon:9: type error in initializer of variable
-expected: i32
-actual: Bool
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/global_variable4.carbon b/executable_semantics/testdata/global_variable4.carbon
index 85547c23d1cf..744a0fe91c29 100644
--- a/executable_semantics/testdata/global_variable4.carbon
+++ b/executable_semantics/testdata/global_variable4.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/global_variable4.golden b/executable_semantics/testdata/global_variable4.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/global_variable4.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/global_variable5.carbon b/executable_semantics/testdata/global_variable5.carbon
index cdfa9bbb78d1..11f4321a5d83 100644
--- a/executable_semantics/testdata/global_variable5.carbon
+++ b/executable_semantics/testdata/global_variable5.carbon
@@ -1,6 +1,16 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/global_variable5.carbon:22: type error in return
+// CHECK: expected: ()
+// CHECK: actual: i32
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/global_variable5.golden b/executable_semantics/testdata/global_variable5.golden
deleted file mode 100644
index d120bd52d2a4..000000000000
--- a/executable_semantics/testdata/global_variable5.golden
+++ /dev/null
@@ -1,4 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/global_variable5.carbon:12: type error in return
-expected: ()
-actual: i32
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/global_variable6.carbon b/executable_semantics/testdata/global_variable6.carbon
index 893140a76c08..4e8faeb1ae32 100644
--- a/executable_semantics/testdata/global_variable6.carbon
+++ b/executable_semantics/testdata/global_variable6.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/global_variable6.golden b/executable_semantics/testdata/global_variable6.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/global_variable6.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/global_variable7.carbon b/executable_semantics/testdata/global_variable7.carbon
index 5e1dd2843f34..8d19798ecdac 100644
--- a/executable_semantics/testdata/global_variable7.carbon
+++ b/executable_semantics/testdata/global_variable7.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/global_variable7.golden b/executable_semantics/testdata/global_variable7.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/global_variable7.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/global_variable8.carbon b/executable_semantics/testdata/global_variable8.carbon
index 84bb66471679..e8de448604c4 100644
--- a/executable_semantics/testdata/global_variable8.carbon
+++ b/executable_semantics/testdata/global_variable8.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: RUNTIME ERROR: {{.*}}/global_variable8.carbon:18: could not find `y`
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/global_variable8.golden b/executable_semantics/testdata/global_variable8.golden
deleted file mode 100644
index e73ffd2d7204..000000000000
--- a/executable_semantics/testdata/global_variable8.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-RUNTIME ERROR: executable_semantics/testdata/global_variable8.carbon:10: could not find `y`
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/if_else.carbon b/executable_semantics/testdata/if_else.carbon
index d28979f7d947..d531d7be18f4 100644
--- a/executable_semantics/testdata/if_else.carbon
+++ b/executable_semantics/testdata/if_else.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/if_else.golden b/executable_semantics/testdata/if_else.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/if_else.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/if_else_if.carbon b/executable_semantics/testdata/if_else_if.carbon
index 37b2a25600f4..3fd4d594eb93 100644
--- a/executable_semantics/testdata/if_else_if.carbon
+++ b/executable_semantics/testdata/if_else_if.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/if_else_if.golden b/executable_semantics/testdata/if_else_if.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/if_else_if.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/if_else_if_else.carbon b/executable_semantics/testdata/if_else_if_else.carbon
index 1b549aeda330..f5769483cf71 100644
--- a/executable_semantics/testdata/if_else_if_else.carbon
+++ b/executable_semantics/testdata/if_else_if_else.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/if_else_if_else.golden b/executable_semantics/testdata/if_else_if_else.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/if_else_if_else.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/if_false.carbon b/executable_semantics/testdata/if_false.carbon
index 822f11279d24..6971028c4050 100644
--- a/executable_semantics/testdata/if_false.carbon
+++ b/executable_semantics/testdata/if_false.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/if_false.golden b/executable_semantics/testdata/if_false.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/if_false.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/if_nesting.carbon b/executable_semantics/testdata/if_nesting.carbon
index 42c064209b78..619a24ed56f6 100644
--- a/executable_semantics/testdata/if_nesting.carbon
+++ b/executable_semantics/testdata/if_nesting.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/if_nesting.golden b/executable_semantics/testdata/if_nesting.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/if_nesting.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/if_true.carbon b/executable_semantics/testdata/if_true.carbon
index 44ebdf4247f7..979e2badec72 100644
--- a/executable_semantics/testdata/if_true.carbon
+++ b/executable_semantics/testdata/if_true.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/if_true.golden b/executable_semantics/testdata/if_true.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/if_true.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/ignored_parameter.carbon b/executable_semantics/testdata/ignored_parameter.carbon
index a0b371add49a..42b14718873d 100644
--- a/executable_semantics/testdata/ignored_parameter.carbon
+++ b/executable_semantics/testdata/ignored_parameter.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/ignored_parameter.golden b/executable_semantics/testdata/ignored_parameter.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/ignored_parameter.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/import_late.carbon b/executable_semantics/testdata/import_late.carbon
index 09d20e885c4c..d4dd763f75cf 100644
--- a/executable_semantics/testdata/import_late.carbon
+++ b/executable_semantics/testdata/import_late.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/import_late.carbon:19: syntax error, unexpected IMPORT, expecting END_OF_FILE
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/import_late.golden b/executable_semantics/testdata/import_late.golden
deleted file mode 100644
index a91a205e1caa..000000000000
--- a/executable_semantics/testdata/import_late.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/import_late.carbon:11: syntax error, unexpected IMPORT, expecting END_OF_FILE
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/import_nonexistent_library.carbon b/executable_semantics/testdata/import_nonexistent_library.carbon
index 787c0b15b929..44c6d2085320 100644
--- a/executable_semantics/testdata/import_nonexistent_library.carbon
+++ b/executable_semantics/testdata/import_nonexistent_library.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/import_nonexistent_library.golden b/executable_semantics/testdata/import_nonexistent_library.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/import_nonexistent_library.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/import_nonexistent_package.carbon b/executable_semantics/testdata/import_nonexistent_package.carbon
index ebdad887f62b..eafa9359d2df 100644
--- a/executable_semantics/testdata/import_nonexistent_package.carbon
+++ b/executable_semantics/testdata/import_nonexistent_package.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/import_nonexistent_package.golden b/executable_semantics/testdata/import_nonexistent_package.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/import_nonexistent_package.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/invalid_char.carbon b/executable_semantics/testdata/invalid_char.carbon
index 081c298f731f..a9d9f773de7b 100644
--- a/executable_semantics/testdata/invalid_char.carbon
+++ b/executable_semantics/testdata/invalid_char.carbon
@@ -1 +1,13 @@
-þ
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/invalid_char.carbon:13: invalid character '\xEF' in source file.
+
+
+�
diff --git a/executable_semantics/testdata/invalid_char.golden b/executable_semantics/testdata/invalid_char.golden
deleted file mode 100644
index 46c5219e3de6..000000000000
--- a/executable_semantics/testdata/invalid_char.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/invalid_char.carbon:1: invalid character '\xFE' in source file.
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/lit.cfg b/executable_semantics/testdata/lit.cfg
new file mode 100644
index 000000000000..77b1d1b010b4
--- /dev/null
+++ b/executable_semantics/testdata/lit.cfg
@@ -0,0 +1,9 @@
+# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+# Exceptions. See /LICENSE for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+import lit.formats
+
+config.name = 'lit'
+config.suffixes = ['.carbon']
+config.test_format = lit.formats.ShTest()
diff --git a/executable_semantics/testdata/match_any_int.carbon b/executable_semantics/testdata/match_any_int.carbon
index 00dd65e3a35e..8f7b8fca1bca 100644
--- a/executable_semantics/testdata/match_any_int.carbon
+++ b/executable_semantics/testdata/match_any_int.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/match_any_int.golden b/executable_semantics/testdata/match_any_int.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/match_any_int.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/match_int.carbon b/executable_semantics/testdata/match_int.carbon
index f31e4e275fa6..2917b461657b 100644
--- a/executable_semantics/testdata/match_int.carbon
+++ b/executable_semantics/testdata/match_int.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/match_int.golden b/executable_semantics/testdata/match_int.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/match_int.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/match_int_default.carbon b/executable_semantics/testdata/match_int_default.carbon
index 274d6ee1fc45..6474e52f9b08 100644
--- a/executable_semantics/testdata/match_int_default.carbon
+++ b/executable_semantics/testdata/match_int_default.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/match_int_default.golden b/executable_semantics/testdata/match_int_default.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/match_int_default.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/match_placeholder.carbon b/executable_semantics/testdata/match_placeholder.carbon
index e86732e12269..02317c92c5d4 100644
--- a/executable_semantics/testdata/match_placeholder.carbon
+++ b/executable_semantics/testdata/match_placeholder.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/match_placeholder.golden b/executable_semantics/testdata/match_placeholder.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/match_placeholder.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/next.carbon b/executable_semantics/testdata/next.carbon
index cb2452b85162..91df326eace6 100644
--- a/executable_semantics/testdata/next.carbon
+++ b/executable_semantics/testdata/next.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/next.golden b/executable_semantics/testdata/next.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/next.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/no_match.carbon b/executable_semantics/testdata/no_match.carbon
index f05a6e8f2f5d..cdd7b57082e0 100644
--- a/executable_semantics/testdata/no_match.carbon
+++ b/executable_semantics/testdata/no_match.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/no_match.golden b/executable_semantics/testdata/no_match.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/no_match.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/package_library.carbon b/executable_semantics/testdata/package_library.carbon
index 9572e7fc52d6..eefd54770721 100644
--- a/executable_semantics/testdata/package_library.carbon
+++ b/executable_semantics/testdata/package_library.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest library "Foo" api;
 
diff --git a/executable_semantics/testdata/package_library.golden b/executable_semantics/testdata/package_library.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/package_library.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/package_missing.carbon b/executable_semantics/testdata/package_missing.carbon
index 7a87538724c8..b8e1e1af644f 100644
--- a/executable_semantics/testdata/package_missing.carbon
+++ b/executable_semantics/testdata/package_missing.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/package_missing.carbon:13: syntax error, unexpected FN, expecting PACKAGE
+
 
 fn main() -> i32 {
   return 0;
diff --git a/executable_semantics/testdata/package_missing.golden b/executable_semantics/testdata/package_missing.golden
deleted file mode 100644
index e3f0427ec0c9..000000000000
--- a/executable_semantics/testdata/package_missing.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/package_missing.carbon:5: syntax error, unexpected FN, expecting PACKAGE
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/pattern_init.carbon b/executable_semantics/testdata/pattern_init.carbon
index d563802a303c..57eba5ca85ed 100644
--- a/executable_semantics/testdata/pattern_init.carbon
+++ b/executable_semantics/testdata/pattern_init.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/pattern_init.golden b/executable_semantics/testdata/pattern_init.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/pattern_init.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/pattern_variable_fail.carbon b/executable_semantics/testdata/pattern_variable_fail.carbon
index ef7d063cb93c..8bf5c0b538bf 100644
--- a/executable_semantics/testdata/pattern_variable_fail.carbon
+++ b/executable_semantics/testdata/pattern_variable_fail.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/pattern_variable_fail.carbon:17: syntax error, unexpected COLON
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/pattern_variable_fail.golden b/executable_semantics/testdata/pattern_variable_fail.golden
deleted file mode 100644
index da738c81abb5..000000000000
--- a/executable_semantics/testdata/pattern_variable_fail.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/pattern_variable_fail.carbon:9: syntax error, unexpected COLON
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/placeholder_variable.carbon b/executable_semantics/testdata/placeholder_variable.carbon
index 3f3afbc442b0..c1256ee39352 100644
--- a/executable_semantics/testdata/placeholder_variable.carbon
+++ b/executable_semantics/testdata/placeholder_variable.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/placeholder_variable.golden b/executable_semantics/testdata/placeholder_variable.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/placeholder_variable.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/print1.carbon b/executable_semantics/testdata/print1.carbon
index 2ef1d7e53ba1..ce9093cee83a 100644
--- a/executable_semantics/testdata/print1.carbon
+++ b/executable_semantics/testdata/print1.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: Hello world!
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/print1.golden b/executable_semantics/testdata/print1.golden
deleted file mode 100644
index f701bed11cfa..000000000000
--- a/executable_semantics/testdata/print1.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-Hello world!
-result: 0
diff --git a/executable_semantics/testdata/record1.carbon b/executable_semantics/testdata/record1.carbon
index 827d555f6b77..c571f639a657 100644
--- a/executable_semantics/testdata/record1.carbon
+++ b/executable_semantics/testdata/record1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/record1.golden b/executable_semantics/testdata/record1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/record1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/return_auto.carbon b/executable_semantics/testdata/return_auto.carbon
index 7da2486a862e..7ba06582a02b 100644
--- a/executable_semantics/testdata/return_auto.carbon
+++ b/executable_semantics/testdata/return_auto.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/return_auto.carbon:15: syntax error, unexpected AUTO
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/return_auto.golden b/executable_semantics/testdata/return_auto.golden
deleted file mode 100644
index 535e5ceca5a3..000000000000
--- a/executable_semantics/testdata/return_auto.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/return_auto.carbon:7: syntax error, unexpected AUTO
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/return_empty_explicit.carbon b/executable_semantics/testdata/return_empty_explicit.carbon
index d2ef7ef3c791..51646f2d9178 100644
--- a/executable_semantics/testdata/return_empty_explicit.carbon
+++ b/executable_semantics/testdata/return_empty_explicit.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/return_empty_explicit.golden b/executable_semantics/testdata/return_empty_explicit.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/return_empty_explicit.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/return_empty_explicit_fail.carbon b/executable_semantics/testdata/return_empty_explicit_fail.carbon
index 9132bdd44be2..24972f5ffb10 100644
--- a/executable_semantics/testdata/return_empty_explicit_fail.carbon
+++ b/executable_semantics/testdata/return_empty_explicit_fail.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/return_empty_explicit_fail.carbon:16: return (); should not provide a return value, to match the function's signature.
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/return_empty_explicit_fail.golden b/executable_semantics/testdata/return_empty_explicit_fail.golden
deleted file mode 100644
index c06187d107f6..000000000000
--- a/executable_semantics/testdata/return_empty_explicit_fail.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/return_empty_explicit_fail.carbon:8: return (); should not provide a return value, to match the function's signature.
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/return_empty_implicit1.carbon b/executable_semantics/testdata/return_empty_implicit1.carbon
index 33d120730f00..03add62bea5e 100644
--- a/executable_semantics/testdata/return_empty_implicit1.carbon
+++ b/executable_semantics/testdata/return_empty_implicit1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/return_empty_implicit1.golden b/executable_semantics/testdata/return_empty_implicit1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/return_empty_implicit1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/return_empty_implicit2.carbon b/executable_semantics/testdata/return_empty_implicit2.carbon
index 5bb27d7df2ab..619e51368f04 100644
--- a/executable_semantics/testdata/return_empty_implicit2.carbon
+++ b/executable_semantics/testdata/return_empty_implicit2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/return_empty_implicit2.golden b/executable_semantics/testdata/return_empty_implicit2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/return_empty_implicit2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/return_empty_implicit_fail1.carbon b/executable_semantics/testdata/return_empty_implicit_fail1.carbon
index 613543fe756b..5dff75012eda 100644
--- a/executable_semantics/testdata/return_empty_implicit_fail1.carbon
+++ b/executable_semantics/testdata/return_empty_implicit_fail1.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/return_empty_implicit_fail1.carbon:16: control-flow reaches end of function that provides a `->` return type without reaching a return statement
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/return_empty_implicit_fail1.golden b/executable_semantics/testdata/return_empty_implicit_fail1.golden
deleted file mode 100644
index 1b758dc4c992..000000000000
--- a/executable_semantics/testdata/return_empty_implicit_fail1.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/return_empty_implicit_fail1.carbon:8: control-flow reaches end of function that provides a `->` return type without reaching a return statement
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/return_empty_implicit_fail2.carbon b/executable_semantics/testdata/return_empty_implicit_fail2.carbon
index f9971ef96d76..a8f825e7cba7 100644
--- a/executable_semantics/testdata/return_empty_implicit_fail2.carbon
+++ b/executable_semantics/testdata/return_empty_implicit_fail2.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/return_empty_implicit_fail2.carbon:16: return; should provide a return value, to match the function's signature.
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/return_empty_implicit_fail2.golden b/executable_semantics/testdata/return_empty_implicit_fail2.golden
deleted file mode 100644
index ffddb39c077e..000000000000
--- a/executable_semantics/testdata/return_empty_implicit_fail2.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/return_empty_implicit_fail2.carbon:8: return; should provide a return value, to match the function's signature.
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/star.carbon b/executable_semantics/testdata/star.carbon
index c1bdd09d3ac3..26a8f1ebff8d 100644
--- a/executable_semantics/testdata/star.carbon
+++ b/executable_semantics/testdata/star.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/star.golden b/executable_semantics/testdata/star.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/star.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/string1.carbon b/executable_semantics/testdata/string1.carbon
index 4405fe85fae8..8b352ea703a6 100644
--- a/executable_semantics/testdata/string1.carbon
+++ b/executable_semantics/testdata/string1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/string1.golden b/executable_semantics/testdata/string1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/string1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/string2.carbon b/executable_semantics/testdata/string2.carbon
index 449c7aa2b903..6cab9df48610 100644
--- a/executable_semantics/testdata/string2.carbon
+++ b/executable_semantics/testdata/string2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/string2.golden b/executable_semantics/testdata/string2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/string2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/string3.carbon b/executable_semantics/testdata/string3.carbon
index 36b91c496592..b816872446cf 100644
--- a/executable_semantics/testdata/string3.carbon
+++ b/executable_semantics/testdata/string3.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/string3.golden b/executable_semantics/testdata/string3.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/string3.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/string_fail1.carbon b/executable_semantics/testdata/string_fail1.carbon
index 67eed54704d9..040ff097f577 100644
--- a/executable_semantics/testdata/string_fail1.carbon
+++ b/executable_semantics/testdata/string_fail1.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/string_fail1.carbon:16: Invalid escaping in string: "str\e"
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/string_fail1.golden b/executable_semantics/testdata/string_fail1.golden
deleted file mode 100644
index 80e4740bbc87..000000000000
--- a/executable_semantics/testdata/string_fail1.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/string_fail1.carbon:8: Invalid escaping in string: "str\e"
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/string_fail2.carbon b/executable_semantics/testdata/string_fail2.carbon
index ee59b401aab0..c214552ae9bf 100644
--- a/executable_semantics/testdata/string_fail2.carbon
+++ b/executable_semantics/testdata/string_fail2.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/string_fail2.carbon:16: Invalid escaping in string: "str\x"
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/string_fail2.golden b/executable_semantics/testdata/string_fail2.golden
deleted file mode 100644
index 082579f4e8f9..000000000000
--- a/executable_semantics/testdata/string_fail2.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/string_fail2.carbon:8: Invalid escaping in string: "str\x"
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/string_fail3.carbon b/executable_semantics/testdata/string_fail3.carbon
index 1d29b32ef7a2..b77ffba067bd 100644
--- a/executable_semantics/testdata/string_fail3.carbon
+++ b/executable_semantics/testdata/string_fail3.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/string_fail3.carbon:16: Invalid escaping in string: "str\xaa"
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/string_fail3.golden b/executable_semantics/testdata/string_fail3.golden
deleted file mode 100644
index ab8183d12496..000000000000
--- a/executable_semantics/testdata/string_fail3.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/string_fail3.carbon:8: Invalid escaping in string: "str\xaa"
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/string_fail4.carbon b/executable_semantics/testdata/string_fail4.carbon
index db1679afe72e..163627f25c9c 100644
--- a/executable_semantics/testdata/string_fail4.carbon
+++ b/executable_semantics/testdata/string_fail4.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/string_fail4.carbon:16: Invalid escaping in string: "str\01"
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/string_fail4.golden b/executable_semantics/testdata/string_fail4.golden
deleted file mode 100644
index e6a4890ca300..000000000000
--- a/executable_semantics/testdata/string_fail4.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/string_fail4.carbon:8: Invalid escaping in string: "str\01"
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/string_fail5.carbon b/executable_semantics/testdata/string_fail5.carbon
index 7d22e729deae..fb092a9a249d 100644
--- a/executable_semantics/testdata/string_fail5.carbon
+++ b/executable_semantics/testdata/string_fail5.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/string_fail5.carbon:16: invalid character '\x22' in source file.
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/string_fail5.golden b/executable_semantics/testdata/string_fail5.golden
deleted file mode 100644
index 2fb63e7df106..000000000000
--- a/executable_semantics/testdata/string_fail5.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/string_fail5.carbon:8: invalid character '\x22' in source file.
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/string_fail6.carbon b/executable_semantics/testdata/string_fail6.carbon
index b418a5c6c6dd..152a0d92c7eb 100644
--- a/executable_semantics/testdata/string_fail6.carbon
+++ b/executable_semantics/testdata/string_fail6.carbon
@@ -1,6 +1,14 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/string_fail6.carbon:16: Invalid escaping in string: "new	line"
+
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/string_fail6.golden b/executable_semantics/testdata/string_fail6.golden
deleted file mode 100644
index 25467b3a874a..000000000000
--- a/executable_semantics/testdata/string_fail6.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/string_fail6.carbon:8: Invalid escaping in string: "new	line"
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/tuple1.carbon b/executable_semantics/testdata/tuple1.carbon
index 1cf887a99e9b..6d1c5c062d17 100644
--- a/executable_semantics/testdata/tuple1.carbon
+++ b/executable_semantics/testdata/tuple1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple1.golden b/executable_semantics/testdata/tuple1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/tuple1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/tuple2.carbon b/executable_semantics/testdata/tuple2.carbon
index d306a662a69f..74af0289ca53 100644
--- a/executable_semantics/testdata/tuple2.carbon
+++ b/executable_semantics/testdata/tuple2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple2.golden b/executable_semantics/testdata/tuple2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/tuple2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/tuple3.carbon b/executable_semantics/testdata/tuple3.carbon
index 92e2f79942cc..c1cbc542555a 100644
--- a/executable_semantics/testdata/tuple3.carbon
+++ b/executable_semantics/testdata/tuple3.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple3.golden b/executable_semantics/testdata/tuple3.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/tuple3.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/tuple4.carbon b/executable_semantics/testdata/tuple4.carbon
index 81e357402677..832b8628a5aa 100644
--- a/executable_semantics/testdata/tuple4.carbon
+++ b/executable_semantics/testdata/tuple4.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: PROGRAM ERROR: {{.*}}/tuple4.carbon:15: positional members must come before named members
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple4.golden b/executable_semantics/testdata/tuple4.golden
deleted file mode 100644
index f65afac4c2ea..000000000000
--- a/executable_semantics/testdata/tuple4.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-PROGRAM ERROR: executable_semantics/testdata/tuple4.carbon:8: positional members must come before named members
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/tuple5.carbon b/executable_semantics/testdata/tuple5.carbon
index e9b5ee2d9fdd..53eba00a67c1 100644
--- a/executable_semantics/testdata/tuple5.carbon
+++ b/executable_semantics/testdata/tuple5.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: PROGRAM ERROR: {{.*}}/tuple5.carbon:17: Tuple field name 'y' does not match pattern field name 'x'
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple5.golden b/executable_semantics/testdata/tuple5.golden
deleted file mode 100644
index fcb8cdbc1969..000000000000
--- a/executable_semantics/testdata/tuple5.golden
+++ /dev/null
@@ -1,2 +0,0 @@
-PROGRAM ERROR: executable_semantics/testdata/tuple5.carbon:10: Tuple field name 'y' does not match pattern field name 'x'
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/tuple_assign.carbon b/executable_semantics/testdata/tuple_assign.carbon
index 2d9af23520b0..0598c59737cc 100644
--- a/executable_semantics/testdata/tuple_assign.carbon
+++ b/executable_semantics/testdata/tuple_assign.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple_assign.golden b/executable_semantics/testdata/tuple_assign.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/tuple_assign.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/tuple_equality.carbon b/executable_semantics/testdata/tuple_equality.carbon
index b77b5ac6dbce..55f8eace112f 100644
--- a/executable_semantics/testdata/tuple_equality.carbon
+++ b/executable_semantics/testdata/tuple_equality.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple_equality.golden b/executable_semantics/testdata/tuple_equality.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/tuple_equality.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/tuple_equality2.carbon b/executable_semantics/testdata/tuple_equality2.carbon
index be5821bef8c3..124f67ca0d6b 100644
--- a/executable_semantics/testdata/tuple_equality2.carbon
+++ b/executable_semantics/testdata/tuple_equality2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple_equality2.golden b/executable_semantics/testdata/tuple_equality2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/tuple_equality2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/tuple_equality3.carbon b/executable_semantics/testdata/tuple_equality3.carbon
index 0f7b119d67f6..c86edb49b810 100644
--- a/executable_semantics/testdata/tuple_equality3.carbon
+++ b/executable_semantics/testdata/tuple_equality3.carbon
@@ -1,6 +1,8 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: not executable_semantics %s 2>&1 2>&1 | FileCheck %s
 
 package ExecutableSemanticsTest api;
 
@@ -13,3 +15,8 @@ fn main() -> i32 {
     return 0;
   }
 }
+
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/tuple_equality3.carbon:12: type error in ==
+// CHECK: expected: (0 = i32, 1 = i32)
+// CHECK: actual: (0 = i32)
diff --git a/executable_semantics/testdata/tuple_equality3.golden b/executable_semantics/testdata/tuple_equality3.golden
deleted file mode 100644
index 2b6f0679e047..000000000000
--- a/executable_semantics/testdata/tuple_equality3.golden
+++ /dev/null
@@ -1,4 +0,0 @@
-COMPILATION ERROR: executable_semantics/testdata/tuple_equality3.carbon:10: type error in ==
-expected: (0 = i32, 1 = i32)
-actual: (0 = i32)
-EXIT CODE: 255
diff --git a/executable_semantics/testdata/tuple_match.carbon b/executable_semantics/testdata/tuple_match.carbon
index c3d558b4d2c7..4860c591a061 100644
--- a/executable_semantics/testdata/tuple_match.carbon
+++ b/executable_semantics/testdata/tuple_match.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple_match.golden b/executable_semantics/testdata/tuple_match.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/tuple_match.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/tuple_match2.carbon b/executable_semantics/testdata/tuple_match2.carbon
index 1179d06bde78..4408f8a7b1f3 100644
--- a/executable_semantics/testdata/tuple_match2.carbon
+++ b/executable_semantics/testdata/tuple_match2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple_match2.golden b/executable_semantics/testdata/tuple_match2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/tuple_match2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/tuple_match3.carbon b/executable_semantics/testdata/tuple_match3.carbon
index 00529664b0fa..b63826b06351 100644
--- a/executable_semantics/testdata/tuple_match3.carbon
+++ b/executable_semantics/testdata/tuple_match3.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/tuple_match3.golden b/executable_semantics/testdata/tuple_match3.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/tuple_match3.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/type_compute.carbon b/executable_semantics/testdata/type_compute.carbon
index 7d8fe94715fc..953ae01196e8 100644
--- a/executable_semantics/testdata/type_compute.carbon
+++ b/executable_semantics/testdata/type_compute.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/type_compute.golden b/executable_semantics/testdata/type_compute.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/type_compute.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/type_compute2.carbon b/executable_semantics/testdata/type_compute2.carbon
index 6336d982cea8..04495543eaa7 100644
--- a/executable_semantics/testdata/type_compute2.carbon
+++ b/executable_semantics/testdata/type_compute2.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/type_compute2.golden b/executable_semantics/testdata/type_compute2.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/type_compute2.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/type_compute3.carbon b/executable_semantics/testdata/type_compute3.carbon
index 4125272eec91..1aee168da663 100644
--- a/executable_semantics/testdata/type_compute3.carbon
+++ b/executable_semantics/testdata/type_compute3.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/type_compute3.golden b/executable_semantics/testdata/type_compute3.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/type_compute3.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/type_match.carbon b/executable_semantics/testdata/type_match.carbon
index 2b838ac1f8bd..d14b60c4bfa8 100644
--- a/executable_semantics/testdata/type_match.carbon
+++ b/executable_semantics/testdata/type_match.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/type_match.golden b/executable_semantics/testdata/type_match.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/type_match.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/while1.carbon b/executable_semantics/testdata/while1.carbon
index fd42d3aa4e2d..fe2ac8739c0f 100644
--- a/executable_semantics/testdata/while1.carbon
+++ b/executable_semantics/testdata/while1.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/while1.golden b/executable_semantics/testdata/while1.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/while1.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/testdata/zero.carbon b/executable_semantics/testdata/zero.carbon
index 2cf5bf104a42..fe24e4a58a10 100644
--- a/executable_semantics/testdata/zero.carbon
+++ b/executable_semantics/testdata/zero.carbon
@@ -1,6 +1,13 @@
 // Part of the Carbon Language project, under the Apache License v2.0 with LLVM
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
 
 package ExecutableSemanticsTest api;
 
diff --git a/executable_semantics/testdata/zero.golden b/executable_semantics/testdata/zero.golden
deleted file mode 100644
index 2db2755da426..000000000000
--- a/executable_semantics/testdata/zero.golden
+++ /dev/null
@@ -1 +0,0 @@
-result: 0
diff --git a/executable_semantics/tests.py b/executable_semantics/tests.py
deleted file mode 100755
index 2406f6eb0417..000000000000
--- a/executable_semantics/tests.py
+++ /dev/null
@@ -1,170 +0,0 @@
-#!/usr/bin/env python3
-
-"""Helps manage tests."""
-
-__copyright__ = """
-Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-Exceptions. See /LICENSE for license information.
-SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-"""
-
-import argparse
-from concurrent import futures
-import os
-import re
-import subprocess
-import sys
-
-_BINDIR = "./bazel-bin/executable_semantics"
-_TESTDATA = "executable_semantics/testdata"
-_TEST_LIST_BZL = "executable_semantics/test_list.bzl"
-
-_TEST_LIST_HEADER = """
-# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-# Exceptions. See /LICENSE for license information.
-# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-\"""Auto-generated list of tests. Run `./tests.py --update_list` to update.\"""
-
-TEST_LIST = [
-"""
-
-_TEST_LIST_FOOTER = """
-]
-"""
-
-
-def _parse_args(args=None):
-    """Parses command-line arguments and flags."""
-    parser = argparse.ArgumentParser(description=__doc__)
-    group = parser.add_mutually_exclusive_group(required=True)
-    group.add_argument(
-        "--update_all",
-        action="store_true",
-        help="Runs all updates.",
-    )
-    group.add_argument(
-        "--update_goldens",
-        action="store_true",
-        help="Updates golden files by running executable_semantics.",
-    )
-    group.add_argument(
-        "--update_list", action="store_true", help="Updates test_list.bzl."
-    )
-    parser.add_argument(
-        "--use_git_ls_files",
-        action="store_true",
-        help="Uses `git ls-files` when gathering files for --update_list.",
-    )
-    parsed_args = parser.parse_args(args=args)
-    if parsed_args.use_git_ls_files and not (
-        parsed_args.update_list or parsed_args.update_all
-    ):
-        parser.error("--use_git_ls_files requires --update_list")
-    return parsed_args
-
-
-def _update_list(use_git_state):
-    """Updates test_list.bzl."""
-    # Get the list of tests and goldens from the filesystem.
-    tests = set()
-    goldens = set()
-    if use_git_state:
-        ls_files = subprocess.check_output(["git", "ls-files", _TESTDATA])
-        files = ls_files.decode("utf-8").splitlines()
-    else:
-        files = list(os.listdir(_TESTDATA))
-    for path in files:
-        f = os.path.basename(path)
-        basename, ext = os.path.splitext(f)
-        if ext == ".carbon":
-            tests.add(basename)
-        elif ext == ".golden":
-            goldens.add(basename)
-        else:
-            sys.exit("Unrecognized file type in testdata: %s" % f)
-
-    # Update test_list.bzl if needed, creating any missing golden files too.
-    test_list = _TEST_LIST_HEADER.lstrip("\n")
-    for test in sorted(tests):
-        test_list += '    "%s",\n' % test
-        if test not in goldens:
-            print("Creating empty golden '%s.golden' for test." % test)
-            open(os.path.join(_TESTDATA, "%s.golden" % test), "w").close()
-    test_list += _TEST_LIST_FOOTER.lstrip("\n")
-    bzl_content = open(_TEST_LIST_BZL).read()
-    if bzl_content != test_list:
-        print("Updating test_list.bzl")
-        with open(_TEST_LIST_BZL, "w") as bzl:
-            bzl.write(test_list)
-    else:
-        print("test_list.bzl is up-to-date")
-
-    # Garbage collect unnecessary golden files.
-    for golden in sorted(goldens):
-        if golden not in tests:
-            filename = "%s.golden" % golden
-            print("Removing golden '%s' because it has no test." % filename)
-            os.unlink(os.path.join(_TESTDATA, filename))
-
-
-def _update_golden(test):
-    """Updates the golden file for `test` by running executable_semantics."""
-    # Invoke the test update directly in order to allow parallel execution
-    # (`bazel run` will serialize).
-    p = subprocess.run(
-        [
-            "%s/%s_test" % (_BINDIR, test),
-            "%s/%s.golden" % (_TESTDATA, test),
-            "%s/executable_semantics %s/%s.carbon" % (_BINDIR, _TESTDATA, test),
-            "--update",
-        ],
-        stdout=subprocess.PIPE,
-        stderr=subprocess.STDOUT,
-    )
-    if p.returncode != 0:
-        out = p.stdout.decode("utf-8")
-        print(out, file=sys.stderr, end="")
-        sys.exit("ERROR: Updating test '%s' failed" % test)
-    print(".", end="", flush=True)
-
-
-def _update_goldens():
-    """Runs bazel to update golden files."""
-    # Load tests from the bzl file. This isn't done through os.listdir because
-    # building new tests requires --update_list.
-    bzl_content = open(_TEST_LIST_BZL).read()
-    tests = re.findall(r'"(\w+)",', bzl_content)
-
-    # Build all tests at once in order to allow parallel updates.
-    print("Building tests...")
-    subprocess.check_call(
-        [
-            "bazel",
-            "build",
-            "//executable_semantics:golden_tests",
-        ],
-    )
-
-    print("Updating %d goldens..." % len(tests))
-    with futures.ThreadPoolExecutor() as exec:
-        # list() iterates to propagate exceptions.
-        list([exec.map(_update_golden, tests)])
-    # Each golden indicates progress with a dot without a newline, so put a
-    # newline to wrap.
-    print("\nUpdated goldens.")
-
-
-def main():
-    # Go to the repository root so that paths will match bazel's view.
-    os.chdir(os.path.join(os.path.dirname(__file__), ".."))
-
-    parsed_args = _parse_args()
-    if parsed_args.update_all or parsed_args.update_list:
-        _update_list(parsed_args.use_git_ls_files)
-    if parsed_args.update_all or parsed_args.update_goldens:
-        _update_goldens()
-
-
-if __name__ == "__main__":
-    main()
diff --git a/executable_semantics/update_checks.py b/executable_semantics/update_checks.py
new file mode 100755
index 000000000000..e88a8705dc14
--- /dev/null
+++ b/executable_semantics/update_checks.py
@@ -0,0 +1,103 @@
+#!/usr/bin/env python3
+
+"""Updates the CHECK: lines in lit tests based on the AUTOUPDATE line."""
+
+__copyright__ = """
+Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+Exceptions. See /LICENSE for license information.
+SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+"""
+
+from concurrent import futures
+import os
+import subprocess
+import sys
+
+_BINDIR = "./bazel-bin/executable_semantics"
+_TESTDATA = "executable_semantics/testdata"
+
+# TODO: Right now this is a static string used. In theory maybe we should use
+# the command; it's included for that flexibility.
+_AUTOUPDATE_MARKER = "// AUTOUPDATE: executable_semantics %s\n"
+
+
+def _get_tests():
+    """Get the list of tests from the filesystem."""
+    tests = set()
+    for path in list(os.listdir(_TESTDATA)):
+        f = os.path.basename(path)
+        if f == "lit.cfg":
+            # Ignore the lit config.
+            continue
+        basename, ext = os.path.splitext(f)
+        if ext == ".carbon":
+            tests.add(basename)
+        else:
+            sys.exit("Unrecognized file type in testdata: %s" % f)
+    return tests
+
+
+def _update_check(test):
+    """Updates the CHECK: lines for `test` by running executable_semantics."""
+    test_file = "%s/%s.carbon" % (_TESTDATA, test)
+    with open(test_file) as f:
+        orig_lines = f.readlines()
+    if _AUTOUPDATE_MARKER not in orig_lines:
+        raise ValueError("No autoupdate marker in %s" % test_file)
+    # Run executable_semantics to general output.
+    # (`bazel run` would serialize)
+    p = subprocess.run(
+        ["%s/executable_semantics" % _BINDIR, test_file],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT,
+    )
+    out = p.stdout.decode("utf-8")
+
+    # `lit` uses full paths to the test file, so use a regex to ignore paths
+    # when used.
+    # TODO: Maybe revisit and see if lit can be convinced to give a
+    # root-relative path.
+    out = out.replace(test_file, "{{.*}}/%s.carbon" % test)
+
+    # Remove old OUT.
+    lines_without_check = [
+        x for x in orig_lines if not x.startswith("// CHECK:")
+    ]
+    autoupdate_index = lines_without_check.index(_AUTOUPDATE_MARKER)
+    assert autoupdate_index >= 0
+    with open(test_file, "w") as f:
+        f.writelines(lines_without_check[: autoupdate_index + 1])
+        f.writelines(["// CHECK: %s\n" % x for x in out.splitlines()])
+        f.writelines(lines_without_check[autoupdate_index + 1 :])
+
+    print(".", end="", flush=True)
+
+
+def _update_checks():
+    """Runs bazel to update CHECK: lines in lit tests."""
+    # TODO: It may be helpful if a list of tests can be passed in args; would
+    # want to use argparse for this.
+    tests = _get_tests()
+
+    # Build all tests at once in order to allow parallel updates.
+    print("Building executable_semantics...")
+    subprocess.check_call(["bazel", "build", "//executable_semantics"])
+
+    print("Updating %d lit tests..." % len(tests))
+    with futures.ThreadPoolExecutor() as exec:
+        # list() iterates to propagate exceptions.
+        list(exec.map(_update_check, tests))
+    # Each update call indicates progress with a dot without a newline, so put a
+    # newline to wrap.
+    print("\nUpdated lit tests.")
+
+
+def main():
+    # Go to the repository root so that paths will match bazel's view.
+    os.chdir(os.path.join(os.path.dirname(__file__), ".."))
+
+    _update_checks()
+
+
+if __name__ == "__main__":
+    main()