diff --git a/testing/file_test/file_test_base.cpp b/testing/file_test/file_test_base.cpp
index 3946f4d0afec..f9f724a133f0 100644
--- a/testing/file_test/file_test_base.cpp
+++ b/testing/file_test/file_test_base.cpp
@@ -35,6 +35,9 @@ ABSL_FLAG(bool, autoupdate, false,
 ABSL_FLAG(unsigned int, threads, 0,
           "Number of threads to use when autoupdating tests, or 0 to "
           "automatically determine a thread count.");
+ABSL_FLAG(bool, dump_output, false,
+          "Instead of verifying files match test output, directly dump output "
+          "to stderr.");
 
 namespace Carbon::Testing {
 
@@ -66,20 +69,25 @@ static auto SplitOutput(llvm::StringRef output)
 // Runs a test and compares output. This keeps output split by line so that
 // issues are a little easier to identify by the different line.
 auto FileTestBase::TestBody() -> void {
-  std::optional<llvm::PrettyStackTraceFormat> stack_trace_entry;
+  std::string test_command;
+  std::optional<llvm::PrettyStackTraceString> stack_trace_entry;
 
   // If we're being run from bazel, provide some assistance for understanding
   // and reproducing failures.
   const char* target = getenv("TEST_TARGET");
   if (target) {
+    constexpr const char* CommandFormat =
+        "bazel {0} {1} --test_arg=--file_tests={2}";
+    test_command = llvm::formatv(CommandFormat, "test", target, test_name_);
+    // Add a crash trace entry with the run command.
+    stack_trace_entry.emplace(test_command.c_str());
+
     // This advice overrides the --file_tests flag provided by the file_test
     // rule.
-    llvm::errs() << "\nTo test this file alone, run:\n  bazel test " << target
-                 << " --test_arg=--file_tests=" << test_name_ << "\n\n";
-
-    // Add a crash trace entry with a command that runs this test in isolation.
-    stack_trace_entry.emplace("bazel test %s --test_arg=--file_tests=%s",
-                              target, test_name_);
+    llvm::errs() << "\nTo test this file alone, run:\n  " << test_command
+                 << "\n\nTo view output, run:\n  "
+                 << llvm::formatv(CommandFormat, "run", target, test_name_)
+                 << " --test_arg=--dump_output\n\n";
   }
 
   TestContext context;
@@ -159,8 +167,9 @@ auto FileTestBase::RunAutoupdater(const TestContext& context, bool dry_run)
 
 auto FileTestBase::Autoupdate() -> ErrorOr<bool> {
   // Add a crash trace entry mentioning which file we're updating.
-  llvm::PrettyStackTraceFormat stack_trace_entry("performing autoupdate for %s",
-                                                 test_name_);
+  std::string stack_trace_string =
+      llvm::formatv("performing autoupdate for {0}", test_name_);
+  llvm::PrettyStackTraceString stack_trace_entry(stack_trace_string.c_str());
 
   TestContext context;
   auto run_result = ProcessTestFileAndRun(context);
@@ -171,6 +180,25 @@ auto FileTestBase::Autoupdate() -> ErrorOr<bool> {
   return RunAutoupdater(context, /*dry_run=*/false);
 }
 
+auto FileTestBase::DumpOutput() -> ErrorOr<Success> {
+  TestContext context;
+  std::string banner(79, '=');
+  banner.append("\n");
+  llvm::errs() << banner << "= " << test_name_ << "\n";
+
+  auto run_result = ProcessTestFileAndRun(context);
+  if (!run_result.ok()) {
+    return ErrorBuilder() << "Error updating " << test_name_ << ": "
+                          << run_result.error();
+  }
+  llvm::errs() << banner << "= stderr\n"
+               << banner << context.stderr << banner << "= stdout\n"
+               << banner << context.stdout << banner << "= Exit with success: "
+               << (context.exit_with_success ? "true" : "false") << "\n"
+               << banner;
+  return Success();
+}
+
 auto FileTestBase::GetLineNumberReplacements(
     llvm::ArrayRef<llvm::StringRef> filenames)
     -> llvm::SmallVector<LineNumberReplacement> {
@@ -741,6 +769,10 @@ static auto Main(int argc, char** argv) -> int {
                  << error.message() << "\n";
     return EXIT_FAILURE;
   }
+  if (absl::GetFlag(FLAGS_autoupdate) && absl::GetFlag(FLAGS_dump_output)) {
+    llvm::errs() << "--autoupdate and --dump_output are mutually exclusive.\n";
+    return EXIT_FAILURE;
+  }
 
   llvm::SmallVector<std::string> tests = GetTests();
   auto test_factory = GetFileTestFactory();
@@ -765,6 +797,16 @@ static auto Main(int argc, char** argv) -> int {
     pool.wait();
     llvm::errs() << "\nDone!\n";
     return EXIT_SUCCESS;
+  } else if (absl::GetFlag(FLAGS_dump_output)) {
+    for (const auto& test_name : tests) {
+      std::unique_ptr<FileTestBase> test(test_factory.factory_fn(test_name));
+      auto result = test->DumpOutput();
+      if (!result.ok()) {
+        llvm::errs() << "\n" << result.error().message() << "\n";
+      }
+    }
+    llvm::errs() << "\nDone!\n";
+    return EXIT_SUCCESS;
   } else {
     for (llvm::StringRef test_name : tests) {
       testing::RegisterTest(test_factory.name, test_name.data(), nullptr,
diff --git a/testing/file_test/file_test_base.h b/testing/file_test/file_test_base.h
index 2e12883eec36..6437529ab08e 100644
--- a/testing/file_test/file_test_base.h
+++ b/testing/file_test/file_test_base.h
@@ -87,6 +87,9 @@ class FileTestBase : public testing::Test {
   // Runs the test and autoupdates checks. Returns true if updated.
   auto Autoupdate() -> ErrorOr<bool>;
 
+  // Runs the test and dumps output.
+  auto DumpOutput() -> ErrorOr<Success>;
+
   // Returns the name of the test (relative to the repo root).
   auto test_name() const -> llvm::StringRef { return test_name_; }