Index: Lib/lib2to3/main.py
===================================================================
--- Lib/lib2to3/main.py	(revision 67665)
+++ Lib/lib2to3/main.py	(working copy)
@@ -6,6 +6,7 @@
 import os
 import logging
 import optparse
+import shutil
 
 from . import refactor
 
@@ -39,6 +40,7 @@
         # Actually write the new file
         super(StdoutRefactoringTool, self).write_file(new_text,
                                                       filename, old_text)
+        shutil.copymode(backup, filename)
 
     def print_output(self, lines):
         for line in lines: