diff --git a/llvm/utils/update_test_checks.py b/llvm/utils/update_test_checks.py
--- a/llvm/utils/update_test_checks.py
+++ b/llvm/utils/update_test_checks.py
@@ -59,7 +59,7 @@
 
   script_name = os.path.basename(__file__)
   opt_basename = os.path.basename(initial_args.opt_binary)
-  if not re.match(r'^opt(-\d+)?$', opt_basename):
+  if not re.match(r'^opt(-\d+)?(\.exe)?$', opt_basename):
     common.error('Unexpected opt name: ' + opt_basename)
     sys.exit(1)
   opt_basename = 'opt'