diff -r 84cd07899baf Lib/test/test_cmd_line.py
--- a/Lib/test/test_cmd_line.py	Tue Oct 23 14:39:34 2012 +0300
+++ b/Lib/test/test_cmd_line.py	Fri Oct 26 00:28:20 2012 +0300
@@ -4,7 +4,8 @@
 
 import test.test_support, unittest
 import sys
-from test.script_helper import spawn_python, kill_python, python_exit_code
+from test.script_helper import (spawn_python, kill_python, python_exit_code,
+    assert_python_failure)
 
 
 class CmdLineTest(unittest.TestCase):
@@ -101,6 +102,14 @@
         data = self.start_python('-R', '-c', code)
         self.assertTrue('hash_randomization=1' in data)
 
+    def test_unknown_options(self):
+        # Add "without='-E'" to prevent _assert_python append env_vars -E
+        # which changes the output of stderr
+        rc, out, err = assert_python_failure('-z', without='-E')
+        self.assertIn(b'Unknown option', err)
+        self.assertEqual(err.splitlines().count(b'Unknown option: -z'), 1)
+        self.assertEqual(b'', out)
+
 def test_main():
     test.test_support.run_unittest(CmdLineTest)
     test.test_support.reap_children()
diff -r 84cd07899baf Python/getopt.c
--- a/Python/getopt.c	Tue Oct 23 14:39:34 2012 +0300
+++ b/Python/getopt.c	Fri Oct 26 00:28:20 2012 +0300
@@ -41,7 +41,7 @@
 
 void _PyOS_ResetGetOpt(void)
 {
-    _PyOS_opterr = 1;
+    _PyOS_opterr = 0;   /* prevent printing the error in 2nd loop in main.c */
     _PyOS_optind = 1;
     _PyOS_optarg = NULL;
     opt_ptr = "";
@@ -86,17 +86,19 @@
         opt_ptr = &argv[_PyOS_optind++][1];
     }
 
-    if ( (option = *opt_ptr++) == '\0')
+    if ((option = *opt_ptr++) == '\0')
         return -1;
 
     if (option == 'J') {
-        fprintf(stderr, "-J is reserved for Jython\n");
+        if (_PyOS_opterr)
+            fprintf(stderr, "-J is reserved for Jython\n");
         return '_';
     }
 
     if (option == 'X') {
-        fprintf(stderr,
-          "-X is reserved for implementation-specific arguments\n");
+        if (_PyOS_opterr)
+            fprintf(stderr,
+                "-X is reserved for implementation-specific arguments\n");
         return '_';
     }
 
@@ -117,7 +119,7 @@
             if (_PyOS_optind >= argc) {
                 if (_PyOS_opterr)
                     fprintf(stderr,
-                "Argument expected for the -%c option\n", option);
+                        "Argument expected for the -%c option\n", option);
                 return '_';
             }