diff --git a/clang/tools/clang-format/clang-format-diff.py b/clang/tools/clang-format/clang-format-diff.py
--- a/clang/tools/clang-format/clang-format-diff.py
+++ b/clang/tools/clang-format/clang-format-diff.py
@@ -58,6 +58,11 @@
   parser.add_argument('-style',
                       help='formatting style to apply (LLVM, GNU, Google, Chromium, '
                       'Microsoft, Mozilla, WebKit)')
+  parser.add_argument('-fallback-style',
+                      help='The name of the predefined style used as a'
+                      'fallback in case clang-format is invoked with'
+                      '-style=file, but can not find the .clang-format'
+                      'file to use.')
   parser.add_argument('-binary', default='clang-format',
                       help='location of binary to use for clang-format')
   args = parser.parse_args()
@@ -103,6 +108,8 @@
     command.extend(lines)
     if args.style:
       command.extend(['-style', args.style])
+    if args.fallback_style:
+      command.extend(['-fallback-style', args.fallback_style])
 
     try:
       p = subprocess.Popen(command,