diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
old mode 100644
new mode 100755
index 906a7c1..3f65758
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -236,6 +236,11 @@ const LANGUAGE_LOCKED = 2;
 const LANGUAGE_ALL = 3;
 
 /**
+ * The language state used when referring to the site default language .
+ */
+const LANGUAGE_DEFAULT = 4;
+
+/**
  * The type of language used to define the content language.
  */
 const LANGUAGE_TYPE_CONTENT = 'language_content';
@@ -2794,6 +2799,15 @@ function language_list($flags = LANGUAGE_CONFIGURABLE) {
   // default we remove the locked languages, but the caller may request for
   // those languages to be added as well.
   $filtered_languages = array();
+
+  // Add the site's default language if flagged as allowed value.
+  if ($flags & LANGUAGE_DEFAULT) {
+    $default = isset($default) ? $default : language_default();
+    // Rename the default language.
+    $default->name = t("Site's default language");
+    $filtered_languages['site_default'] = $default;
+  }
+
   foreach ($languages as $langcode => $language) {
     if (($language->locked && !($flags & LANGUAGE_LOCKED)) || (!$language->locked && !($flags & LANGUAGE_CONFIGURABLE))) {
       continue;
diff --git a/core/includes/language.inc b/core/includes/language.inc
index 2a0defa..436dd57 100644
--- a/core/includes/language.inc
+++ b/core/includes/language.inc
@@ -408,7 +408,7 @@ function language_negotiation_info() {
     // Add the default language negotiation method.
     $negotiation_info[LANGUAGE_NEGOTIATION_DEFAULT] = array(
       'callbacks' => array('language' => 'language_from_default'),
-      'weight' => 10,
+      'weight' => 14,
       'name' => t('Default language'),
       'description' => t('Use the default site language (@language_name).', array('@language_name' => language_default()->name)),
       'config' => 'admin/config/regional/language',
diff --git a/core/modules/language/language.admin.inc b/core/modules/language/language.admin.inc
old mode 100644
new mode 100755
index af2b3b1..5634dd2
--- a/core/modules/language/language.admin.inc
+++ b/core/modules/language/language.admin.inc
@@ -519,6 +519,7 @@ function language_negotiation_configure_form_table(&$form, $type) {
         '#title_display' => 'invisible',
         '#default_value' => $weight,
         '#attributes' => array('class' => array("language-method-weight-$type")),
+        '#delta' => 20,
       );
 
       $table_form['title'][$method_id] = array('#markup' => $method_name);
@@ -815,6 +816,20 @@ function language_negotiation_configure_session_form($form, &$form_state) {
 }
 
 /**
+ * Builds the selected language negotiation method configuration form.
+ */
+function language_negotiation_configure_selected_form($form, &$form_state) {
+  $form['language_negotiation_selected_langcode'] = array(
+    '#type' => 'language_select',
+    '#title' => t('Language'),
+    '#languages' => LANGUAGE_CONFIGURABLE | LANGUAGE_DEFAULT,
+    '#default_value' => variable_get('language_negotiation_selected_langcode', FALSE),
+  );
+
+  return system_settings_form($form);
+}
+
+/**
  * Builds the browser language negotiation method configuration form.
  */
 function language_negotiation_configure_browser_form($form, &$form_state) {
diff --git a/core/modules/language/language.module b/core/modules/language/language.module
old mode 100644
new mode 100755
index 5b62382..8257810
--- a/core/modules/language/language.module
+++ b/core/modules/language/language.module
@@ -135,6 +135,14 @@ function language_menu() {
     'access arguments' => array('administer languages'),
     'file' => 'language.admin.inc',
   );
+  $items['admin/config/regional/language/detection/selected'] = array(
+    'title' => 'Selected language detection configuration',
+    'page callback' => 'drupal_get_form',
+    'page arguments' => array('language_negotiation_configure_selected_form'),
+    'access arguments' => array('administer languages'),
+    'file' => 'language.admin.inc',
+    'type' => MENU_VISIBLE_IN_BREADCRUMB,
+  );
 
   return $items;
 }
@@ -448,6 +456,15 @@ function language_language_negotiation_info() {
     'description' => t('Account administration pages language setting.'),
   );
 
+  $negotiation_info[LANGUAGE_NEGOTIATION_SELECTED] = array(
+    'callbacks' => array('negotiation' => 'language_from_selected'),
+    'file' => $file,
+    'weight' => 12,
+    'name' => t('Selected'),
+    'description' => t('Language based on a selected language.'),
+    'config' => 'admin/config/regional/language/detection/selected',
+  );
+
   return $negotiation_info;
 }
 
diff --git a/core/modules/language/language.negotiation.inc b/core/modules/language/language.negotiation.inc
old mode 100644
new mode 100755
index fa6a517..a5016ee
--- a/core/modules/language/language.negotiation.inc
+++ b/core/modules/language/language.negotiation.inc
@@ -36,6 +36,11 @@ const LANGUAGE_NEGOTIATION_USER = 'language-user';
 const LANGUAGE_NEGOTIATION_USER_ADMIN = 'language-user-admin';
 
 /**
+ *  The language is set based on a configured language.
+ */
+const LANGUAGE_NEGOTIATION_SELECTED = 'language-selected';
+
+/**
  * The language is set based on the request/session parameters.
  */
 const LANGUAGE_NEGOTIATION_SESSION = 'language-session';
@@ -316,6 +321,24 @@ function language_from_url($languages, $request) {
 }
 
 /**
+ * Identifies language from configuration.
+ *
+ * @param $languages
+ *   An array of valid language objects.
+ *
+ * @return
+ *   A valid language code on success, FALSE otherwise.
+ */
+function language_from_selected($languages) {
+  $langcode = variable_get('language_negotiation_selected_langcode', FALSE);
+  // Replace the site's default langcode by its real value.
+  if ($langcode == 'site_default') {
+    $langcode = language_from_default();
+  }
+  return isset($languages[$langcode]) ? $langcode : FALSE;
+}
+
+/**
  * Determines the language to be assigned to URLs when none is detected.
  *
  * The language negotiation process has a fallback chain that ends with the
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php
index 0b87a09..35b1a39 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php
@@ -140,6 +140,43 @@ class LanguageUILanguageNegotiationTest extends WebTestBase {
     // Configure URL language rewrite.
     variable_set('language_negotiation_url_type', LANGUAGE_TYPE_INTERFACE);
 
+    // Configure selected language negotiation to use zh-hans.
+    $edit = array('language_negotiation_selected_langcode' => $langcode);
+    $this->drupalPost('admin/config/regional/language/detection/selected', $edit, t('Save configuration'));
+    $test = array(
+      'language_negotiation' => array(LANGUAGE_NEGOTIATION_SELECTED, LANGUAGE_NEGOTIATION_DEFAULT),
+      'path' => 'admin/config',
+      'expect' => $language_string,
+      'expected_method_id' => LANGUAGE_NEGOTIATION_SELECTED,
+      'http_header' => $http_header_browser_fallback,
+      'message' => 'SELECTED > DEFAULT: UI language is switched based on selected language.',
+    );
+    $this->runTest($test);
+
+    // An invalid language is selected.
+    variable_set('language_negotiation_selected_langcode', NULL);
+    $test = array(
+      'language_negotiation' => array(LANGUAGE_NEGOTIATION_SELECTED, LANGUAGE_NEGOTIATION_DEFAULT),
+      'path' => 'admin/config',
+      'expect' => $default_string,
+      'expected_method_id' => LANGUAGE_NEGOTIATION_DEFAULT,
+      'http_header' => $http_header_browser_fallback,
+      'message' => 'SELECTED > DEFAULT: UI language is switched based on selected language.',
+    );
+    $this->runTest($test);
+
+    // No selected language is available.
+    variable_set('language_negotiation_selected_langcode', $langcode_unknown);
+    $test = array(
+      'language_negotiation' => array(LANGUAGE_NEGOTIATION_SELECTED, LANGUAGE_NEGOTIATION_DEFAULT),
+      'path' => 'admin/config',
+      'expect' => $default_string,
+      'expected_method_id' => LANGUAGE_NEGOTIATION_DEFAULT,
+      'http_header' => $http_header_browser_fallback,
+      'message' => 'SELECTED > DEFAULT: UI language is switched based on selected language.',
+    );
+    $this->runTest($test);
+
     $tests = array(
       // Default, browser preference should have no influence.
       array(