diff --git a/Lib/test/test__osx_support.py b/Lib/test/test__osx_support.py
new file mode 100644
index 0000000..1f6ceb6
--- /dev/null
+++ b/Lib/test/test__osx_support.py
@@ -0,0 +1,279 @@
+"""
+Test suite for _osx_support: shared OS X support functions.
+"""
+
+import os
+import platform
+import shutil
+import stat
+import sys
+import unittest
+
+import test.test_support
+
+import _osx_support
+
+@unittest.skipUnless(sys.platform.startswith("darwin"), "requires OS X")
+class Test_OSXSupport(unittest.TestCase):
+
+    def setUp(self):
+        self.maxDiff = None
+        self.prog_name = 'bogus_program_xxxx'
+        self.temp_path_dir = os.path.abspath(os.getcwd())
+        self.env = test.test_support.EnvironmentVarGuard()
+        self.addCleanup(self.env.__exit__)
+        for cv in ('CFLAGS', 'LDFLAGS', 'CPPFLAGS',
+                            'BASECFLAGS', 'BLDSHARED', 'LDSHARED', 'CC',
+                            'CXX', 'PY_CFLAGS', 'PY_LDFLAGS', 'PY_CPPFLAGS',
+                            'PY_CORE_CFLAGS'):
+            if cv in self.env:
+                self.env.unset(cv)
+
+    def add_expected_saved_initial_values(self, config_vars, expected_vars):
+        # Ensure that the initial values for all modified config vars
+        # are also saved with modified keys.
+        expected_vars.update(('_OSX_SUPPORT_INITIAL_'+ k,
+                config_vars[k]) for k in config_vars
+                    if config_vars[k] != expected_vars[k])
+
+    def test__find_executable(self):
+        if self.env['PATH']:
+            self.env['PATH'] = self.env['PATH'] + ':'
+        self.env['PATH'] = self.env['PATH'] + os.path.abspath(self.temp_path_dir)
+        test.test_support.unlink(self.prog_name)
+        self.assertIsNone(_osx_support._find_executable(self.prog_name))
+        self.addCleanup(test.test_support.unlink, self.prog_name)
+        with open(self.prog_name, 'w') as f:
+            f.write("#!/bin/sh\n/bin/echo OK\n")
+        os.chmod(self.prog_name, stat.S_IRWXU)
+        self.assertEqual(self.prog_name,
+                            _osx_support._find_executable(self.prog_name))
+
+    def test__read_output(self):
+        if self.env['PATH']:
+            self.env['PATH'] = self.env['PATH'] + ':'
+        self.env['PATH'] = self.env['PATH'] + os.path.abspath(self.temp_path_dir)
+        test.test_support.unlink(self.prog_name)
+        self.addCleanup(test.test_support.unlink, self.prog_name)
+        with open(self.prog_name, 'w') as f:
+            f.write("#!/bin/sh\n/bin/echo ExpectedOutput\n")
+        os.chmod(self.prog_name, stat.S_IRWXU)
+        self.assertEqual('ExpectedOutput',
+                            _osx_support._read_output(self.prog_name))
+
+    def test__find_build_tool(self):
+        out = _osx_support._find_build_tool('cc')
+        self.assertTrue(os.path.isfile(out),
+                            'cc not found - check xcode-select')
+
+    def test__get_system_version(self):
+        self.assertTrue(platform.mac_ver()[0].startswith(
+                                    _osx_support._get_system_version()))
+
+    def test__remove_original_values(self):
+        config_vars = {
+        'CC': 'gcc-test -pthreads',
+        }
+        expected_vars = {
+        'CC': 'clang -pthreads',
+        }
+        cv = 'CC'
+        newvalue = 'clang -pthreads'
+        _osx_support._save_modified_value(config_vars, cv, newvalue)
+        self.assertNotEqual(expected_vars, config_vars)
+        _osx_support._remove_original_values(config_vars)
+        self.assertEqual(expected_vars, config_vars)
+
+    def test__save_modified_value(self):
+        config_vars = {
+        'CC': 'gcc-test -pthreads',
+        }
+        expected_vars = {
+        'CC': 'clang -pthreads',
+        }
+        self.add_expected_saved_initial_values(config_vars, expected_vars)
+        cv = 'CC'
+        newvalue = 'clang -pthreads'
+        _osx_support._save_modified_value(config_vars, cv, newvalue)
+        self.assertEqual(expected_vars, config_vars)
+
+    def test__save_modified_value_unchanged(self):
+        config_vars = {
+        'CC': 'gcc-test -pthreads',
+        }
+        expected_vars = config_vars.copy()
+        cv = 'CC'
+        newvalue = 'gcc-test -pthreads'
+        _osx_support._save_modified_value(config_vars, cv, newvalue)
+        self.assertEqual(expected_vars, config_vars)
+
+    def test__supports_universal_builds(self):
+        import platform
+        self.assertEqual(platform.mac_ver()[0].split('.') >= ['10', '4'],
+                            _osx_support._supports_universal_builds())
+
+    def test__find_appropriate_compiler(self):
+        compilers = (
+                        ('gcc-test', 'i686-apple-darwin11-llvm-gcc-4.2'),
+                        ('clang', 'clang version 3.1'),
+                    )
+        config_vars = {
+        'CC': 'gcc-test -pthreads',
+        'CXX': 'cc++-test',
+        'CFLAGS': '-fno-strict-aliasing  -g -O3 -arch ppc -arch i386  ',
+        'LDFLAGS': '-arch ppc -arch i386   -g',
+        'CPPFLAGS': '-I. -isysroot /Developer/SDKs/MacOSX10.4u.sdk',
+        'BLDSHARED': 'gcc-test -bundle -arch ppc -arch i386 -g',
+        'LDSHARED': 'gcc-test -bundle -arch ppc -arch i386 '
+                        '-isysroot /Developer/SDKs/MacOSX10.4u.sdk -g',
+        }
+        expected_vars = {
+        'CC': 'clang -pthreads',
+        'CXX': 'clang++',
+        'CFLAGS': '-fno-strict-aliasing  -g -O3 -arch ppc -arch i386  ',
+        'LDFLAGS': '-arch ppc -arch i386   -g',
+        'CPPFLAGS': '-I. -isysroot /Developer/SDKs/MacOSX10.4u.sdk',
+        'BLDSHARED': 'clang -bundle -arch ppc -arch i386 -g',
+        'LDSHARED': 'clang -bundle -arch ppc -arch i386 '
+                        '-isysroot /Developer/SDKs/MacOSX10.4u.sdk -g',
+        }
+        self.add_expected_saved_initial_values(config_vars, expected_vars)
+
+        suffix = (':' + self.env['PATH']) if self.env['PATH'] else ''
+        self.env['PATH'] = os.path.abspath(self.temp_path_dir) + suffix
+        for c_name, c_output in compilers:
+            test.test_support.unlink(c_name)
+            self.addCleanup(test.test_support.unlink, c_name)
+            with open(c_name, 'w') as f:
+                f.write("#!/bin/sh\n/bin/echo " + c_output)
+            os.chmod(c_name, stat.S_IRWXU)
+        self.assertEqual(expected_vars,
+                            _osx_support._find_appropriate_compiler(
+                                    config_vars))
+
+    def test__remove_universal_flags(self):
+        config_vars = {
+        'CFLAGS': '-fno-strict-aliasing  -g -O3 -arch ppc -arch i386  ',
+        'LDFLAGS': '-arch ppc -arch i386   -g',
+        'CPPFLAGS': '-I. -isysroot /Developer/SDKs/MacOSX10.4u.sdk',
+        'BLDSHARED': 'gcc-4.0 -bundle  -arch ppc -arch i386 -g',
+        'LDSHARED': 'gcc-4.0 -bundle  -arch ppc -arch i386 '
+                        '-isysroot /Developer/SDKs/MacOSX10.4u.sdk -g',
+        }
+        expected_vars = {
+        'CFLAGS': '-fno-strict-aliasing  -g -O3    ',
+        'LDFLAGS': '    -g',
+        'CPPFLAGS': '-I.  ',
+        'BLDSHARED': 'gcc-4.0 -bundle    -g',
+        'LDSHARED': 'gcc-4.0 -bundle      -g',
+        }
+        self.add_expected_saved_initial_values(config_vars, expected_vars)
+
+        self.assertEqual(expected_vars,
+                            _osx_support._remove_universal_flags(
+                                    config_vars))
+
+    def test__remove_unsupported_archs(self):
+        config_vars = {
+        'CC': 'clang',
+        'CFLAGS': '-fno-strict-aliasing  -g -O3 -arch ppc -arch i386  ',
+        'LDFLAGS': '-arch ppc -arch i386   -g',
+        'CPPFLAGS': '-I. -isysroot /Developer/SDKs/MacOSX10.4u.sdk',
+        'BLDSHARED': 'gcc-4.0 -bundle  -arch ppc -arch i386 -g',
+        'LDSHARED': 'gcc-4.0 -bundle  -arch ppc -arch i386 '
+                        '-isysroot /Developer/SDKs/MacOSX10.4u.sdk -g',
+        }
+        expected_vars = {
+        'CC': 'clang',
+        'CFLAGS': '-fno-strict-aliasing  -g -O3  -arch i386  ',
+        'LDFLAGS': ' -arch i386   -g',
+        'CPPFLAGS': '-I. -isysroot /Developer/SDKs/MacOSX10.4u.sdk',
+        'BLDSHARED': 'gcc-4.0 -bundle   -arch i386 -g',
+        'LDSHARED': 'gcc-4.0 -bundle   -arch i386 '
+                        '-isysroot /Developer/SDKs/MacOSX10.4u.sdk -g',
+        }
+        self.add_expected_saved_initial_values(config_vars, expected_vars)
+
+        suffix = (':' + self.env['PATH']) if self.env['PATH'] else ''
+        self.env['PATH'] = os.path.abspath(self.temp_path_dir) + suffix
+        c_name = 'clang'
+        test.test_support.unlink(c_name)
+        self.addCleanup(test.test_support.unlink, c_name)
+        # exit status 255 means no PPC support in this compiler chain
+        with open(c_name, 'w') as f:
+            f.write("#!/bin/sh\nexit 255")
+        os.chmod(c_name, stat.S_IRWXU)
+        self.assertEqual(expected_vars,
+                            _osx_support._remove_unsupported_archs(
+                                    config_vars))
+
+    def test__override_all_archs(self):
+        self.env['ARCHFLAGS'] = '-arch x86_64'
+        config_vars = {
+        'CC': 'clang',
+        'CFLAGS': '-fno-strict-aliasing  -g -O3 -arch ppc -arch i386  ',
+        'LDFLAGS': '-arch ppc -arch i386   -g',
+        'CPPFLAGS': '-I. -isysroot /Developer/SDKs/MacOSX10.4u.sdk',
+        'BLDSHARED': 'gcc-4.0 -bundle  -arch ppc -arch i386 -g',
+        'LDSHARED': 'gcc-4.0 -bundle -arch ppc -arch i386 '
+                        '-isysroot /Developer/SDKs/MacOSX10.4u.sdk -g',
+        }
+        expected_vars = {
+        'CC': 'clang',
+        'CFLAGS': '-fno-strict-aliasing  -g -O3     -arch x86_64',
+        'LDFLAGS': '    -g -arch x86_64',
+        'CPPFLAGS': '-I. -isysroot /Developer/SDKs/MacOSX10.4u.sdk',
+        'BLDSHARED': 'gcc-4.0 -bundle    -g -arch x86_64',
+        'LDSHARED': 'gcc-4.0 -bundle   -isysroot '
+                        '/Developer/SDKs/MacOSX10.4u.sdk -g -arch x86_64',
+        }
+        self.add_expected_saved_initial_values(config_vars, expected_vars)
+
+        self.assertEqual(expected_vars,
+                            _osx_support._override_all_archs(
+                                    config_vars))
+
+    def test__check_for_unavailable_sdk(self):
+        config_vars = {
+        'CC': 'clang',
+        'CFLAGS': '-fno-strict-aliasing  -g -O3 -arch ppc -arch i386  '
+                        '-isysroot /Developer/SDKs/MacOSX10.1.sdk',
+        'LDFLAGS': '-arch ppc -arch i386   -g',
+        'CPPFLAGS': '-I. -isysroot /Developer/SDKs/MacOSX10.1.sdk',
+        'BLDSHARED': 'gcc-4.0 -bundle  -arch ppc -arch i386 -g',
+        'LDSHARED': 'gcc-4.0 -bundle  -arch ppc -arch i386 '
+                        '-isysroot /Developer/SDKs/MacOSX10.1.sdk -g',
+        }
+        expected_vars = {
+        'CC': 'clang',
+        'CFLAGS': '-fno-strict-aliasing  -g -O3 -arch ppc -arch i386  '
+                        ' ',
+        'LDFLAGS': '-arch ppc -arch i386   -g',
+        'CPPFLAGS': '-I.  ',
+        'BLDSHARED': 'gcc-4.0 -bundle  -arch ppc -arch i386 -g',
+        'LDSHARED': 'gcc-4.0 -bundle  -arch ppc -arch i386 '
+                        ' -g',
+        }
+        self.add_expected_saved_initial_values(config_vars, expected_vars)
+
+        self.assertEqual(expected_vars,
+                            _osx_support._check_for_unavailable_sdk(
+                                    config_vars))
+
+    def test_get_platform_osx(self):
+        # Note, get_platform_osx is currently tested more extensively
+        # indirectly by test_sysconfig and test_distutils
+        config_vars = {
+        'CFLAGS': '-fno-strict-aliasing  -g -O3 -arch ppc -arch i386  '
+                        '-isysroot /Developer/SDKs/MacOSX10.1.sdk',
+        'MACOSX_DEPLOYMENT_TARGET': '10.6',
+        }
+        result = _osx_support.get_platform_osx(config_vars, ' ', ' ', ' ')
+        self.assertEqual(('macosx', '10.6', 'fat'), result)
+
+def test_main():
+    if sys.platform == 'darwin':
+        test.test_support.run_unittest(Test_OSXSupport)
+
+if __name__ == "__main__":
+    test_main()
diff --git a/Lib/test/test_sysconfig.py b/Lib/test/test_sysconfig.py
index 716fa5e..755f35f 100644
--- a/Lib/test/test_sysconfig.py
+++ b/Lib/test/test_sysconfig.py
@@ -14,6 +14,7 @@
                        get_path, get_path_names, _INSTALL_SCHEMES,
                        _get_default_scheme, _expand_vars,
                        get_scheme_names, get_config_var)
+import _osx_support
 
 class TestSysConfig(unittest.TestCase):
 
@@ -137,6 +138,7 @@
                    ('Darwin Kernel Version 8.11.1: '
                     'Wed Oct 10 18:23:28 PDT 2007; '
                     'root:xnu-792.25.20~1/RELEASE_I386'), 'PowerPC'))
+        _osx_support._remove_original_values(get_config_vars())
         get_config_vars()['MACOSX_DEPLOYMENT_TARGET'] = '10.3'
 
         get_config_vars()['CFLAGS'] = ('-fno-strict-aliasing -DNDEBUG -g '
@@ -156,6 +158,7 @@
                    ('Darwin Kernel Version 8.11.1: '
                     'Wed Oct 10 18:23:28 PDT 2007; '
                     'root:xnu-792.25.20~1/RELEASE_I386'), 'i386'))
+        _osx_support._remove_original_values(get_config_vars())
         get_config_vars()['MACOSX_DEPLOYMENT_TARGET'] = '10.3'
 
         get_config_vars()['CFLAGS'] = ('-fno-strict-aliasing -DNDEBUG -g '
@@ -171,6 +174,7 @@
             sys.maxint = maxint
 
         # macbook with fat binaries (fat, universal or fat64)
+        _osx_support._remove_original_values(get_config_vars())
         get_config_vars()['MACOSX_DEPLOYMENT_TARGET'] = '10.4'
         get_config_vars()['CFLAGS'] = ('-arch ppc -arch i386 -isysroot '
                                        '/Developer/SDKs/MacOSX10.4u.sdk  '
@@ -179,6 +183,7 @@
 
         self.assertEqual(get_platform(), 'macosx-10.4-fat')
 
+        _osx_support._remove_original_values(get_config_vars())
         get_config_vars()['CFLAGS'] = ('-arch x86_64 -arch i386 -isysroot '
                                        '/Developer/SDKs/MacOSX10.4u.sdk  '
                                        '-fno-strict-aliasing -fno-common '
@@ -186,18 +191,21 @@
 
         self.assertEqual(get_platform(), 'macosx-10.4-intel')
 
+        _osx_support._remove_original_values(get_config_vars())
         get_config_vars()['CFLAGS'] = ('-arch x86_64 -arch ppc -arch i386 -isysroot '
                                        '/Developer/SDKs/MacOSX10.4u.sdk  '
                                        '-fno-strict-aliasing -fno-common '
                                        '-dynamic -DNDEBUG -g -O3')
         self.assertEqual(get_platform(), 'macosx-10.4-fat3')
 
+        _osx_support._remove_original_values(get_config_vars())
         get_config_vars()['CFLAGS'] = ('-arch ppc64 -arch x86_64 -arch ppc -arch i386 -isysroot '
                                        '/Developer/SDKs/MacOSX10.4u.sdk  '
                                        '-fno-strict-aliasing -fno-common '
                                        '-dynamic -DNDEBUG -g -O3')
         self.assertEqual(get_platform(), 'macosx-10.4-universal')
 
+        _osx_support._remove_original_values(get_config_vars())
         get_config_vars()['CFLAGS'] = ('-arch x86_64 -arch ppc64 -isysroot '
                                        '/Developer/SDKs/MacOSX10.4u.sdk  '
                                        '-fno-strict-aliasing -fno-common '
@@ -206,6 +214,7 @@
         self.assertEqual(get_platform(), 'macosx-10.4-fat64')
 
         for arch in ('ppc', 'i386', 'x86_64', 'ppc64'):
+            _osx_support._remove_original_values(get_config_vars())
             get_config_vars()['CFLAGS'] = ('-arch %s -isysroot '
                                            '/Developer/SDKs/MacOSX10.4u.sdk  '
                                            '-fno-strict-aliasing -fno-common '