diff --git a/libcxx/utils/compile_only.py b/libcxx/utils/compile_only.py
new file mode 100755
--- /dev/null
+++ b/libcxx/utils/compile_only.py
@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+#===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===----------------------------------------------------------------------===##
+
+"""compile_only.py is a utility for simulating running of a program."""
+
+import argparse
+import subprocess
+import sys
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--execdir', type=str, required=True)
+    parser.add_argument('--codesign_identity', type=str, required=False, default=None)
+    parser.add_argument('--env', type=str, nargs='*', required=False, default=dict())
+    (args, remaining) = parser.parse_known_args(sys.argv[1:])
+
+    if len(remaining) < 2:
+        sys.stderr.write('Missing actual commands to run')
+        exit(1)
+    commandLine = remaining[1:] # Skip the '--'
+
+    # Do any necessary codesigning.
+    if args.codesign_identity:
+        exe = commandLine[0]
+        rc = subprocess.call(['xcrun', 'codesign', '-f', '-s', args.codesign_identity, exe], env={})
+        if rc != 0:
+            sys.stderr.write('Failed to codesign: ' + exe)
+            return rc
+
+    # Extract environment variables into a dictionary
+    env = {k : v  for (k, v) in map(lambda s: s.split('=', 1), args.env)}
+    # Run the command line with the given environment in the execution directory.
+    print("Would have run", subprocess.list2cmdline(commandLine), "in", args.execdir, "with env=", env)
+
+
+if __name__ == '__main__':
+    exit(main())