diff --git a/clang/test/lit.cfg.py b/clang/test/lit.cfg.py
--- a/clang/test/lit.cfg.py
+++ b/clang/test/lit.cfg.py
@@ -284,6 +284,10 @@
         config.substitutions.append(('llvm-nm', 'env OBJECT_MODE=any llvm-nm'))
         config.substitutions.append(('llvm-ar', 'env OBJECT_MODE=any llvm-ar'))
 
+# Pass the crash diagnostic dir set in the os environment to LIT.
+if 'CLANG_CRASH_DIAGNOSTICS_DIR' in os.environ:
+    config.environment['CLANG_CRASH_DIAGNOSTICS_DIR'] = os.environ['CLANG_CRASH_DIAGNOSTICS_DIR']
+
 # It is not realistically possible to account for all options that could
 # possibly be present in system and user configuration files, so disable
 # default configs for the test runs.