Index: cfe/trunk/test/Driver/lit.local.cfg
===================================================================
--- cfe/trunk/test/Driver/lit.local.cfg
+++ cfe/trunk/test/Driver/lit.local.cfg
@@ -4,3 +4,15 @@
 config.substitutions.insert(0,
     ('%clang_cc1',
      """*** Do not use 'clang -cc1' in Driver tests. ***""") )
+
+# Remove harmful environmental variables for clang Driver tests.
+# Some might be useful for other tests so they are only removed here.
+driver_overwrite_env_vars = ['MACOSX_DEPLOYMENT_TARGET',
+                             'IPHONEOS_DEPLOYMENT_TARGET',
+                             'SDKROOT', 'CCC_OVERRIDE_OPTIONS',
+                             'CC_PRINT_OPTIONS', 'CC_PRINT_HEADERS',
+                             'CC_LOG_DIAGNOSTICS']
+
+for name in driver_overwrite_env_vars:
+  if name in config.environment:
+    del config.environment[name]