diff --git a/modules/system/system.module b/modules/system/system.module
index 9897fb2..0d808d1 100644
--- a/modules/system/system.module
+++ b/modules/system/system.module
@@ -2384,6 +2384,10 @@ function _system_rebuild_module_data() {
       continue;
     }
 
+    // Add the info file modification time, so it becomes available for
+    // contributed modules to use for ordering module lists.
+    $module->info['mtime'] = filemtime(dirname($module->uri) . '/' . $module->name . '.info');
+
     // Merge in defaults and save.
     $modules[$key]->info = $module->info + $defaults;
 
@@ -2522,6 +2526,10 @@ function _system_rebuild_theme_data() {
     $themes[$key]->filename = $theme->uri;
     $themes[$key]->info = drupal_parse_info_file($theme->uri) + $defaults;
 
+    // Add the info file modification time, so it becomes available for
+    // contributed modules to use for ordering theme lists.
+    $themes[$key]->info['mtime'] = filemtime($theme->uri);
+
     // Invoke hook_system_info_alter() to give installed modules a chance to
     // modify the data in the .info files if necessary.
     $type = 'theme';
diff --git a/modules/system/system.test b/modules/system/system.test
index abd21aa..72ca941 100644
--- a/modules/system/system.test
+++ b/modules/system/system.test
@@ -556,6 +556,34 @@ class ModuleDependencyTestCase extends ModuleTestCase {
     $this->drupalPost(NULL, NULL, t('Uninstall'));
     $this->assertText(t('The selected modules have been uninstalled.'), t('Modules status has been updated.'));
   }
+
+  /**
+   * Tests whether the correct module metadata is returned.
+   */
+  function testModuleMetaData() {
+    // Generate the list of available modules.
+    $modules = system_rebuild_module_data();
+    // Check that the mtime field exists for the system module.
+    $this->assertTrue(!empty($modules['system']->info['mtime']), 'The system.info file modification time field is present.');
+    // Use 0 if mtime isn't present, to avoid an array index notice.
+    $test_mtime = !empty($modules['system']->info['mtime']) ? $modules['system']->info['mtime'] : 0;
+    // Ensure the mtime field contains a number that is greater than zero.
+    $this->assertTrue(is_numeric($test_mtime) && ($test_mtime > 0), 'The system.info file modification time field contains a timestamp.');
+  }
+
+  /**
+   * Tests whether the correct theme metadata is returned.
+   */
+  function testThemeMetaData() {
+    // Generate the list of available themes.
+    $themes = system_rebuild_theme_data();
+    // Check that the mtime field exists for the bartik theme.
+    $this->assertTrue(!empty($themes['bartik']->info['mtime']), 'The bartik.info file modification time field is present.');
+    // Use 0 if mtime isn't present, to avoid an array index notice.
+    $test_mtime = !empty($themes['bartik']->info['mtime']) ? $themes['bartik']->info['mtime'] : 0;
+    // Ensure the mtime field contains a number that is greater than zero.
+    $this->assertTrue(is_numeric($test_mtime) && ($test_mtime > 0), 'The bartik.info file modification time field contains a timestamp.');
+  }
 }
 
 /**