diff --git a/core/modules/language/config/language.mappings.yml b/core/modules/language/config/language.mappings.yml
new file mode 100644
index 0000000..913714e
--- /dev/null
+++ b/core/modules/language/config/language.mappings.yml
@@ -0,0 +1,7 @@
+zh-tw: zh-hant-tw
+zh-hk: zh-hant-hk
+zh-mo: zh-hant-mo
+zh-cht: zh-hant
+zh-cn: zh-hans-cn
+zh-sg: zh-hans-sg
+zh-chs: zh-hans
diff --git a/core/modules/language/language.install b/core/modules/language/language.install
index 2884d4b..9e5d982 100644
--- a/core/modules/language/language.install
+++ b/core/modules/language/language.install
@@ -110,6 +110,7 @@ function language_enable() {
   // Update the language count, if the module was disabled before, the
   // language_count variable was forced to 1.
   language_update_count();
+  config_install_default_config('module', 'language');
 }
 
 /**
diff --git a/core/modules/language/language.module b/core/modules/language/language.module
index f90ef93..e7d3e2b 100644
--- a/core/modules/language/language.module
+++ b/core/modules/language/language.module
@@ -596,3 +596,15 @@ function language_url_outbound_alter(&$path, &$options, $original_path) {
     }
   }
 }
+
+/**
+ * Returns default language mappings.
+ * @todo: How can this be overridden?
+ */
+function language_get_mappings() {
+  $config = config('language.mappings');
+  if ($config->isNew()) {
+    return FALSE;
+  }
+  return $config->get();
+}
\ No newline at end of file
diff --git a/core/modules/language/language.negotiation.inc b/core/modules/language/language.negotiation.inc
index 0ff02d8..a363217 100644
--- a/core/modules/language/language.negotiation.inc
+++ b/core/modules/language/language.negotiation.inc
@@ -81,23 +81,18 @@ function language_from_browser($languages) {
   // Samples: "hu, en-us;q=0.66, en;q=0.33", "hu,en-us;q=0.5"
   $browser_langcodes = array();
   if (preg_match_all('@(?<=[, ]|^)([a-zA-Z-]+|\*)(?:;q=([0-9.]+))?(?:$|\s*,\s*)@', trim($_SERVER['HTTP_ACCEPT_LANGUAGE']), $matches, PREG_SET_ORDER)) {
+    // Load custom mappings to support browsers that are sending non standard
+    // language codes.
+    $mappings = language_get_mappings();
     foreach ($matches as $match) {
-      // Handle Chinese so it maps right, some browsers are sending
-      // wrong langcodes.
-      switch (strtolower($match[1])) {
-        case 'zh-tw': // Taiwan.
-        case 'zh-hk': // Hong Kong.
-        case 'zh-mo': // Macau.
-        case 'zh-cht': // Traditional Chinese.
-          $match[1] = 'zh-hant';
-          break;
-        case 'zh-cn': // China.
-        case 'zh-sg': // Singapore.
-        case 'zh-chs': // Simplified Chinese.
-          $match[1] = 'zh-hans';
-          break;
+      if ($mappings) {
+        $langcode = strtolower($match[1]);
+        foreach ($mappings as $browser_langcode => $drupal_langcode) {
+          if ($langcode == $browser_langcode) {
+            $match[1] = $drupal_langcode;
+          }
+        }
       }
-
       // We can safely use strtolower() here, tags are ASCII.
       // RFC2616 mandates that the decimal part is no more than three digits,
       // so we multiply the qvalue by 1000 to avoid floating point comparisons.
@@ -116,8 +111,16 @@ function language_from_browser($languages) {
   // http://blogs.msdn.com/b/ie/archive/2006/10/17/accept-language-header-for-internet-explorer-7.aspx
   asort($browser_langcodes);
   foreach ($browser_langcodes as $langcode => $qvalue) {
-    $generic_tag = strtok($langcode, '-');
-    if (!isset($browser_langcodes[$generic_tag])) {
+    // For chinese languages the generic tag is either zh-hans or zh-hant, so we
+    // need to handle this separately.
+    $generic_tag = '';
+    if (strlen($langcode) > 7 && (substr($langcode, 0, 7) == 'zh-hant' || substr($langcode, 0, 7) == 'zh-hans')) {
+      $generic_tag = substr($langcode, 0, 7);
+    }
+    else {
+      $generic_tag = strtok($langcode, '-');
+    }
+    if (!empty($generic_tag) && !isset($browser_langcodes[$generic_tag])) {
       // Add the generic langcode, but make sure it has a lower qvalue as the
       // more specific one, so the more specific one gets selected if it's
       // defined by both the browser and Drupal.
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageBrowserDetectionUnitTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageBrowserDetectionUnitTest.php
index beb18c5..b34cc93 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageBrowserDetectionUnitTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageBrowserDetectionUnitTest.php
@@ -7,13 +7,15 @@
 
 namespace Drupal\language\Tests;
 
-use Drupal\simpletest\UnitTestBase;
+use Drupal\simpletest\WebTestBase;
 use Drupal\Core\Language\Language;
 
 /**
  * Test browser language detection.
  */
-class LanguageBrowserDetectionUnitTest extends UnitTestBase {
+class LanguageBrowserDetectionUnitTest extends WebTestBase {
+
+  public static $modules = array('language');
 
   public static function getInfo() {
     return array(
@@ -27,9 +29,6 @@ class LanguageBrowserDetectionUnitTest extends UnitTestBase {
    * Unit tests for the language_from_browser() function.
    */
   function testLanguageFromBrowser() {
-    // Load the required functions.
-    require_once DRUPAL_ROOT . '/core/modules/language/language.negotiation.inc';
-
     $languages = array(
       // In our test case, 'en' has priority over 'en-US'.
       'en' => new Language(array(
@@ -65,6 +64,9 @@ class LanguageBrowserDetectionUnitTest extends UnitTestBase {
       'zh-hant' => new Language(array(
         'langcode' => 'zh-hant',
       )),
+      'zh-hant-tw' => new Language(array(
+        'langcode' => 'zh-hant',
+      )),
     );
 
     $test_cases = array(