Index: Lib/argparse.py
===================================================================
--- Lib/argparse.py	(revision 83676)
+++ Lib/argparse.py	(working copy)
@@ -1070,7 +1070,7 @@
             raise ArgumentError(self, msg)
 
         # parse all the remaining options into the namespace
-        parser.parse_args(arg_strings, namespace)
+        parser.parse_args_record_unrecognized(arg_strings, namespace)
 
 
 # ==============
@@ -1659,7 +1659,23 @@
             msg = _('unrecognized arguments: %s')
             self.error(msg % ' '.join(argv))
         return args
+    
+    def parse_args_record_unrecognized(self, args=None, namespace=None):
+        """Allows deferral of decision on whether to exit upon hitting
+           an unrecognized argument, since it may originate either with 
+           parse_args or parse_known_args."""
+        args, argv = self.parse_known_args(args, namespace)
+        if argv:
+            if not hasattr(args, '_unrecognized'):
+                args._unrecognized = []
+            args._unrecognized.extend(argv)
+        return args        
 
+    def retrieve_recorded_unrecognized_args(self, args, argv):
+        if hasattr(args, '_unrecognized'):
+            argv.extend(args._unrecognized)
+            delattr(args, '_unrecognized')
+
     def parse_known_args(self, args=None, namespace=None):
         # args default to the system args
         if args is None:
@@ -1686,7 +1702,9 @@
 
         # parse the arguments and exit if there are any errors
         try:
-            return self._parse_known_args(args, namespace)
+            (recognized, unrecognized) = self._parse_known_args(args, namespace)
+            self.retrieve_recorded_unrecognized_args(recognized, unrecognized)
+            return (recognized, unrecognized)
         except ArgumentError:
             err = _sys.exc_info()[1]
             self.error(str(err))