diff --git a/explorer/common/source_location.h b/explorer/common/source_location.h
index a8f3bb305389..cc46cc37f736 100644
--- a/explorer/common/source_location.h
+++ b/explorer/common/source_location.h
@@ -48,14 +48,20 @@ class SourceLocation {
   auto file_kind() const -> FileKind { return file_kind_; }
 
   void Print(llvm::raw_ostream& out) const {
-    out << filename_ << ":" << line_num_;
+    if (file_kind_ == FileKind::Prelude) {
+      out << llvm::StringRef(filename_).rsplit("/").second << ":" << line_num_;
+    } else {
+      out << filename_ << ":" << line_num_;
+    }
   }
+
   auto ToString() const -> std::string {
     std::string result;
     llvm::raw_string_ostream out(result);
     Print(out);
     return result;
   }
+
   LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }
 
  private:
diff --git a/explorer/testdata/assert/fail_assert.carbon b/explorer/testdata/assert/fail_assert.carbon
index 577c96767a8d..b0cc77a14cab 100644
--- a/explorer/testdata/assert/fail_assert.carbon
+++ b/explorer/testdata/assert/fail_assert.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: "HALLO WELT"
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: "HALLO WELT"
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/assert/fail_convert.carbon b/explorer/testdata/assert/fail_convert.carbon
index 4b4633105444..18cd6988a84a 100644
--- a/explorer/testdata/assert/fail_convert.carbon
+++ b/explorer/testdata/assert/fail_convert.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: "Fail"
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: "Fail"
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/destructor/fail_delete_base_without_virtual_destructor.carbon b/explorer/testdata/destructor/fail_delete_base_without_virtual_destructor.carbon
index f93b2ffc0a6c..2b54b41f924d 100644
--- a/explorer/testdata/destructor/fail_delete_base_without_virtual_destructor.carbon
+++ b/explorer/testdata/destructor/fail_delete_base_without_virtual_destructor.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: Deallocating a derived class from base class pointer requires a virtual destructor
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: Deallocating a derived class from base class pointer requires a virtual destructor
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/operators/fail_left_shift_large_rhs.carbon b/explorer/testdata/operators/fail_left_shift_large_rhs.carbon
index 3eb36e6f090c..ac869897c87c 100644
--- a/explorer/testdata/operators/fail_left_shift_large_rhs.carbon
+++ b/explorer/testdata/operators/fail_left_shift_large_rhs.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: Integer overflow
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: Integer overflow
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/operators/fail_left_shift_negative_rhs.carbon b/explorer/testdata/operators/fail_left_shift_negative_rhs.carbon
index 9866b0e71bfc..7c17f7408e6e 100644
--- a/explorer/testdata/operators/fail_left_shift_negative_rhs.carbon
+++ b/explorer/testdata/operators/fail_left_shift_negative_rhs.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: Integer overflow
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: Integer overflow
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/operators/fail_right_shift_large_rhs.carbon b/explorer/testdata/operators/fail_right_shift_large_rhs.carbon
index 8aa0c384e940..9bdce1d14eb9 100644
--- a/explorer/testdata/operators/fail_right_shift_large_rhs.carbon
+++ b/explorer/testdata/operators/fail_right_shift_large_rhs.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: Integer overflow
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: Integer overflow
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/operators/fail_right_shift_negative_rhs.carbon b/explorer/testdata/operators/fail_right_shift_negative_rhs.carbon
index 9cc9ab6a15bb..1d8fe7ddba40 100644
--- a/explorer/testdata/operators/fail_right_shift_negative_rhs.carbon
+++ b/explorer/testdata/operators/fail_right_shift_negative_rhs.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: Integer overflow
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: Integer overflow
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/optional/fail_optional_get_empty.carbon b/explorer/testdata/optional/fail_optional_get_empty.carbon
index c2f0d1560a69..85778a7dc24d 100644
--- a/explorer/testdata/optional/fail_optional_get_empty.carbon
+++ b/explorer/testdata/optional/fail_optional_get_empty.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: "Attempted to unwrap empty Optional"
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: "Attempted to unwrap empty Optional"
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/random/fail_empty_range.carbon b/explorer/testdata/random/fail_empty_range.carbon
index 81b7d839cd57..ed54d200c287 100644
--- a/explorer/testdata/random/fail_empty_range.carbon
+++ b/explorer/testdata/random/fail_empty_range.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: Rand inputs must be ordered for a non-empty range: 0 must be less than 0
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: Rand inputs must be ordered for a non-empty range: 0 must be less than 0
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/random/fail_reverse_range.carbon b/explorer/testdata/random/fail_reverse_range.carbon
index f8f6ece01961..addae9335c55 100644
--- a/explorer/testdata/random/fail_reverse_range.carbon
+++ b/explorer/testdata/random/fail_reverse_range.carbon
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // AUTOUPDATE
-// CHECK:STDERR: RUNTIME ERROR: /explorer/data/prelude.carbon:{{\d+}}: Rand inputs must be ordered for a non-empty range: 1 must be less than -1
+// CHECK:STDERR: RUNTIME ERROR: prelude.carbon:{{\d+}}: Rand inputs must be ordered for a non-empty range: 1 must be less than -1
 
 package ExplorerTest api;
 
diff --git a/explorer/testdata/trace/context_all.carbon b/explorer/testdata/trace/context_all.carbon
index 43df75e7b11e..b9f177e21ae1 100644
--- a/explorer/testdata/trace/context_all.carbon
+++ b/explorer/testdata/trace/context_all.carbon
@@ -15,7 +15,7 @@ fn Main() -> i32 {
 // ARGS: --trace_file=- --trace_phase=all --trace_file_context=all %s
 // NOAUTOUPDATE
 // SET-CHECK-SUBSET
-// CHECK:STDOUT: *** declaring `interface As` ({{.*}}/explorer/data/prelude.carbon:14)
+// CHECK:STDOUT: *** declaring `interface As` (prelude.carbon:14)
 // CHECK:STDOUT: *** declaring function `Main` (context_all.carbon:11)
 // CHECK:STDOUT: interface As {
 // CHECK:STDOUT: fn Main ()-> i32 {
diff --git a/explorer/testdata/trace/context_prelude.carbon b/explorer/testdata/trace/context_prelude.carbon
index 4794a7f5242b..fea2afd7a5d1 100644
--- a/explorer/testdata/trace/context_prelude.carbon
+++ b/explorer/testdata/trace/context_prelude.carbon
@@ -15,5 +15,5 @@ fn Main() -> i32 {
 // ARGS: --trace_file=- --trace_phase=all --trace_file_context=prelude %s
 // NOAUTOUPDATE
 // SET-CHECK-SUBSET
-// CHECK:STDOUT: *** declaring `interface As` ({{.*}}/explorer/data/prelude.carbon:14)
+// CHECK:STDOUT: *** declaring `interface As` (prelude.carbon:14)
 // CHECK:STDOUT: interface As {