diff --git a/llvm/utils/update_cc_test_checks.py b/llvm/utils/update_cc_test_checks.py
--- a/llvm/utils/update_cc_test_checks.py
+++ b/llvm/utils/update_cc_test_checks.py
@@ -414,7 +414,7 @@
                                output_lines, global_vars_seen_dict, True, False)
     common.debug('Writing %d lines to %s...' % (len(output_lines), ti.path))
     with open(ti.path, 'wb') as f:
-      f.writelines(['{}\n'.format(l).encode('utf-8') for l in output_lines])
+      f.writelines(['{}{}'.format(l, os.linesep).encode('utf-8') for l in output_lines])
 
   return 0