diff --git a/clang/tools/clang-format/clang-format-diff.py b/clang/tools/clang-format/clang-format-diff.py
index 68b5113d92f6..bb18730b63c6 100755
--- a/clang/tools/clang-format/clang-format-diff.py
+++ b/clang/tools/clang-format/clang-format-diff.py
@@ -83,7 +83,7 @@ def formatRange(r, style):
 def main():
   parser = argparse.ArgumentParser(description=
                                    'Reformat changed lines in diff')
-  parser.add_argument('-p', default=1,
+  parser.add_argument('-p', default=0,
                       help='strip the smallest prefix containing P slashes')
   parser.add_argument('-style',
                       help='formatting style to apply (LLVM, Google, Chromium)')