diff --git a/servo/python/mach/mach/dispatcher.py b/servo/python/mach/mach/dispatcher.py
index 6a4916c0fa0c..666c4a3f691d 100644
--- a/servo/python/mach/mach/dispatcher.py
+++ b/servo/python/mach/mach/dispatcher.py
@@ -92,7 +92,6 @@ class CommandAction(argparse.Action):
         elif values:
             command = values[0].lower()
             args = values[1:]
-
             if command == 'help':
                 if args and args[0] not in ['-h', '--help']:
                     # Make sure args[0] is indeed a command.
@@ -102,8 +101,17 @@ class CommandAction(argparse.Action):
                 sys.exit(0)
             elif '-h' in args or '--help' in args:
                 # -h or --help is in the command arguments.
-                self._handle_command_help(parser, command)
-                sys.exit(0)
+                if '--' in args:
+                    # -- is in command arguments
+                    if '-h' in args[:args.index('--')] or '--help' in args[:args.index('--')]:
+                        # Honor -h or --help only if it appears before --
+                        self._handle_command_help(parser, command)
+                        sys.exit(0)
+                else:
+                    self._handle_command_help(parser, command)
+                    sys.exit(0)
+
+
         else:
             raise NoCommandError()
 
@@ -172,14 +180,20 @@ class CommandAction(argparse.Action):
             'usage': usage,
         }
 
+        remainder = None
+
         if handler.parser:
             subparser = handler.parser
             subparser.context = self._context
+            for arg in subparser._actions[:]:
+                if arg.nargs == argparse.REMAINDER:
+                    subparser._actions.remove(arg)
+                    remainder = (arg.dest,), {'default': arg.default,
+                                              'nargs': arg.nargs,
+                                              'help': arg.help}
         else:
             subparser = argparse.ArgumentParser(**parser_args)
 
-        remainder = None
-
         for arg in handler.arguments:
             # Remove our group keyword; it's not needed here.
             group_name = arg[1].get('group')
@@ -230,7 +244,7 @@ class CommandAction(argparse.Action):
                 setattr(command_namespace, name, extra)
             else:
                 setattr(command_namespace, name, options.get('default', []))
-        elif extra:
+        elif extra and handler.cls.__name__ != 'DeprecatedCommands':
             raise UnrecognizedArgumentError(command, extra)
 
     def _handle_main_help(self, parser, verbose):
diff --git a/servo/python/mach/mach/registrar.py b/servo/python/mach/mach/registrar.py
index 49c41bf97bfb..522f761dceee 100644
--- a/servo/python/mach/mach/registrar.py
+++ b/servo/python/mach/mach/registrar.py
@@ -61,6 +61,11 @@ class MachRegistrar(object):
         if handler.pass_context and not context:
             raise Exception('mach command class requires context.')
 
+        if context:
+            prerun = getattr(context, 'pre_dispatch_handler', None)
+            if prerun:
+                prerun(context, handler, args=kwargs)
+
         if handler.pass_context:
             instance = cls(context)
         else: