diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 0dd19d5..4dcf481 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -2743,7 +2743,8 @@ function language($type, $reset = FALSE) {
  *   name and its value is its configurability (TRUE/FALSE).
  */
 function language_types_get_all() {
-  return array_keys(variable_get('language_types', language_types_get_default()));
+  $language_types = config('language.detection')->get('types') ?: language_types_get_default();
+  return array_keys($language_types);
 }
 /**
  * Returns a list of the built-in language types.
@@ -2767,10 +2768,10 @@ function language_types_get_default() {
  *   TRUE if more than one language is enabled.
  */
 function language_multilingual() {
-  // The "language_count" variable stores the number of enabled languages to
-  // avoid unnecessarily querying the database when building the list of
-  // enabled languages on monolingual sites.
-  return variable_get('language_count', 1) > 1;
+  // The "language.detection.count" variable stores the number of enabled
+  // languages to avoid unnecessarily querying the database when building the
+  // list of enabled languages on monolingual sites.
+  return state('language.detection')->get('count') > 1;
 }
 
 /**
@@ -2931,13 +2932,7 @@ function language_is_locked($langcode) {
  *   A language object.
  */
 function language_default() {
-  $info = variable_get('language_default', array(
-    'langcode' => 'en',
-    'name' => 'English',
-    'direction' => 0,
-    'weight' => 0,
-    'locked' => 0,
-  ));
+  $info = config('language.detection')->get('default');
   $info['default'] = TRUE;
   return new Language($info);
 }
diff --git a/core/includes/language.inc b/core/includes/language.inc
index 74d5752..cade907 100644
--- a/core/includes/language.inc
+++ b/core/includes/language.inc
@@ -166,11 +166,11 @@ function language_types_info() {
  * the user interface.
  *
  * @param $stored
- *   (optional) By default, retrieves values from the 'language_types' variable
- *   to avoid unnecessary hook invocations. If set to FALSE, retrieves values
- *   from the actual language type definitions. This allows reaction to
+ *   (optional) By default, retrieves values from the language.detection.types
+ *   variable to avoid unnecessary hook invocations. If set to FALSE, retrieves
+ *   values from the actual language type definitions. This allows reaction to
  *   alterations performed on the definitions by modules installed after the
- *   'language_types' variable is set.
+ *   language.detection.types variable is set.
  *
  * @return
  *   An array of language type names.
@@ -179,7 +179,7 @@ function language_types_get_configurable($stored = TRUE) {
   $configurable = &drupal_static(__FUNCTION__);
 
   if ($stored && !isset($configurable)) {
-    $types = variable_get('language_types', language_types_get_default());
+    $types = config('language.detection')->get('types') ?: language_types_get_default();
     $configurable = array_keys(array_filter($types));
   }
 
@@ -203,13 +203,16 @@ function language_types_get_configurable($stored = TRUE) {
  *   An array of language types.
  */
 function language_types_disable($types) {
-  $enabled_types = variable_get('language_types', language_types_get_default());
+  $language_settings = config('language.detection');
+  $enabled_types = $language_settings->get('types') ?: language_types_get_default();
 
   foreach ($types as $type) {
     unset($enabled_types[$type]);
   }
 
-  variable_set('language_types', $enabled_types);
+  $language_settings
+    ->set('types', $enabled_types)
+    ->save();
 }
 
 /**
@@ -244,7 +247,9 @@ function language_types_set() {
   }
 
   // Save enabled language types.
-  variable_set('language_types', $language_types);
+  config('language.settings')
+    ->set('types', $language_types)
+    ->save();
 
   // Ensure that subsequent calls of language_types_get_configurable() return
   // the updated language type information.
diff --git a/core/includes/update.inc b/core/includes/update.inc
index ec21aca..d61f818 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -197,20 +197,23 @@ function update_prepare_d8_bootstrap() {
       // process.
       drupal_bootstrap(DRUPAL_BOOTSTRAP_VARIABLES);
 
-      // Update the 'language_default' system variable, if configured.
+      // Update the "language.settings.default" system variable, if configured.
       // Required to run before drupal_install_config_directories(), since that
       // triggers a call into system_stream_wrappers(), which calls t(), which
       // calls into language_default().
-      $language_default = variable_get('language_default');
+      $language_settings = config('language.detection');
+      $language_default = $language_settings->get('default');
       if (!empty($language_default) && (isset($language_default->langcode) || isset($language_default->language))) {
         if (!isset($language_default->langcode)) {
           $language_default->langcode = $language_default->language;
         }
         unset($language_default->language);
-        // In D8, the 'language_default' is not anymore an object, but an array,
-        // so make sure that the new value that is saved into this variable is an
-        // array.
-        variable_set('language_default', (array) $language_default);
+        // In D8, the "language.detection.default" variable is not anymore an
+        // object, but an array, so make sure that the new value that is saved
+        // into this variable is an array.
+        $language_settings
+          ->set('default', (array) $language_default)
+          ->save();
       }
 
       $module_config = config('system.module');
@@ -351,7 +354,9 @@ function update_prepare_d8_language() {
     db_drop_field('languages', 'enabled');
 
     // Update language count.
-    variable_set('language_count', db_query('SELECT COUNT(language) FROM {languages}')->fetchField());
+    state('language.detection')
+      ->set('count', db_query('SELECT COUNT(language) FROM {languages}')->fetchField())
+      ->save();
 
     // Rename the languages table to language.
     db_rename_table('languages', 'language');
@@ -401,18 +406,22 @@ function update_prepare_d8_language() {
       }
     }
 
-    // Update the 'language_default' system variable with the langcode change.
-    $language_default = variable_get('language_default');
+    // Update the language.detection.default system variable with the langcode
+    // change.
+    $language_settings = config('language.detection');
+    $language_default = $language_settings->get('default');
     if (!empty($language_default)) {
       if (isset($language_default->language)) {
         $language_default->langcode = $language_default->language;
         unset($language_default->language);
       }
       unset($language_default->enabled);
-      // In D8, the 'language_default' is not anymore an object, but an array,
-      // so make sure that the new value that is saved into this variable is an
-      // array.
-      variable_set('language_default', (array) $language_default);
+      // In D8, language.detection.default is not anymore an object, but an
+      // array, so make sure that the new value that is saved into this variable
+      // is an array.
+      $language_settings
+        ->set('default', (array) $language_default)
+        ->save();
     }
 
     // Add column to track customized string status to locales_target.
diff --git a/core/modules/comment/lib/Drupal/comment/Tests/CommentLanguageTest.php b/core/modules/comment/lib/Drupal/comment/Tests/CommentLanguageTest.php
index a704fb7..26c7ed6 100644
--- a/core/modules/comment/lib/Drupal/comment/Tests/CommentLanguageTest.php
+++ b/core/modules/comment/lib/Drupal/comment/Tests/CommentLanguageTest.php
@@ -56,7 +56,9 @@ function setUp() {
     $this->drupalPost('admin/structure/types/manage/article', $edit, t('Save content type'));
 
     // Enable content language negotiation UI.
-    variable_set('language_test_content_language_type', TRUE);
+    config('language.test')
+      ->set('content_type', TRUE)
+      ->save();
 
     // Set interface language detection to user and content language detection
     // to URL. Disable inheritance from interface language to ensure content
diff --git a/core/modules/field/field.multilingual.inc b/core/modules/field/field.multilingual.inc
index b2e4363..5e0a6fb 100644
--- a/core/modules/field/field.multilingual.inc
+++ b/core/modules/field/field.multilingual.inc
@@ -76,9 +76,10 @@ function field_language_insert() {
   field_info_cache_clear();
   // If the number of languages is bigger than 1, enable the core language
   // fallback rules.
-  // Because the language_count is updated only after the hook is invoked, we
-  // check if the language_count is bigger or equal with 1 at the current time.
-  if (variable_get('language_count', 1) >= 1) {
+  // Because the "language.detection.count" variable is updated only after the
+  // hook is invoked, we check to see if it is bigger or equal with 1 at the
+  // current time.
+  if (state('language.detection')->get('count') >= 1) {
     variable_set('field_language_fallback', TRUE);
   }
 }
@@ -97,9 +98,10 @@ function field_language_delete() {
   field_info_cache_clear();
   // If the number of languages is less than 2, disable the core language
   // fallback rules.
-  // Because the language_count is updated after the hook is invoked, we check
-  // if the language_count is less or equal with 2 at the current time.
-  if (variable_get('language_count', 1) <= 2) {
+  // Because the "language.detection.count" variable is updated after the hook
+  // is invoked, we check to see if it is less than or equal with 2 at the
+  // current time.
+  if (state('language.detection')->get('count') <= 2) {
     variable_set('field_language_fallback', FALSE);
   }
 }
diff --git a/core/modules/language/config/language.detection.yml b/core/modules/language/config/language.detection.yml
index 1299603..9c9ec6d 100644
--- a/core/modules/language/config/language.detection.yml
+++ b/core/modules/language/config/language.detection.yml
@@ -1 +1,8 @@
 selected_langcode: site_default
+count: 1
+default:
+  'langcode': 'en'
+  'name': 'English'
+  'direction': '0'
+  'weight': '0'
+  'locked': '0'
diff --git a/core/modules/language/language.admin.inc b/core/modules/language/language.admin.inc
index d51aa91..8926bd7 100644
--- a/core/modules/language/language.admin.inc
+++ b/core/modules/language/language.admin.inc
@@ -460,7 +460,7 @@ function language_negotiation_configure_form_table(&$form, $type) {
 
   $negotiation_info = $form['#language_negotiation_info'];
   $enabled_methods = variable_get("language_negotiation_$type", array());
-  $methods_weight = variable_get("language_negotiation_methods_weight_$type", array());
+  $methods_weight = config('lanuage.negotiation_methods')->get("weight_$type") ?: array();
 
   // Add missing data to the methods lists.
   foreach ($negotiation_info as $method_id => $method) {
@@ -618,7 +618,9 @@ function language_negotiation_configure_form_submit($form, &$form_state) {
     }
 
     language_negotiation_set($type, $method_weights);
-    variable_set("language_negotiation_methods_weight_$type", $method_weights_input);
+    config('language.negotiation_methods')
+      ->set("methods_weight_$type", $method_weights_input)
+      ->save();
   }
 
   // Update non-configurable language types and the related language negotiation
diff --git a/core/modules/language/language.install b/core/modules/language/language.install
index b16c53b..36a7f23 100644
--- a/core/modules/language/language.install
+++ b/core/modules/language/language.install
@@ -31,20 +31,6 @@ function language_install() {
  * Implements hook_uninstall().
  */
 function language_uninstall() {
-  // Clear variables.
-  variable_del('language_default');
-  variable_del('language_count');
-
-  // Clear variables.
-  variable_del('language_types');
-  variable_del('language_content_type_default');
-  variable_del('language_content_type_negotiation');
-
-  foreach (language_types_get_all() as $type) {
-    variable_del("language_negotiation_$type");
-    variable_del("language_negotiation_methods_weight_$type");
-  }
-
   // Re-initialize the language system so successive calls to t() and other
   // functions will not expect languages to be present.
   drupal_language_initialize();
@@ -104,7 +90,7 @@ function language_schema() {
  */
 function language_enable() {
   // Update the language count, if the module was disabled before, the
-  // language_count variable was forced to 1.
+  // "language.detection.count" variable was forced to 1.
   language_update_count();
 }
 
@@ -112,8 +98,11 @@ function language_enable() {
  * Implements hook_disable().
  */
 function language_disable() {
-  // Force the language_count variable to be 1, so that the when checking if the
-  // site is multilingual (for example in language_multilingual()), the result
-  // will be FALSE, because the language module is disabled.
-  variable_set('language_count', 1);
+  // Force the "language.detection.count" variable to be 1, so that the when
+  // checking if the site is multilingual (for example in
+  // language_multilingual()), the result will be FALSE, because the language
+  // module is disabled.
+  state('language.detection')
+    ->set('count', '1')
+    ->save();
 }
diff --git a/core/modules/language/language.module b/core/modules/language/language.module
index 71135a4..6b62bd5 100644
--- a/core/modules/language/language.module
+++ b/core/modules/language/language.module
@@ -476,7 +476,9 @@ function language_save($language) {
   if (!empty($language->default)) {
     // Set the new version of this language as default in a variable.
     $default_language = language_default();
-    variable_set('language_default', (array) $language);
+    config('language.detection')
+      ->set('default', (array) $language)
+      ->save();
   }
 
   // Update language count based on unlocked language count.
@@ -493,14 +495,16 @@ function language_save($language) {
 }
 
 /**
- * Updates the language_count variable.
+ * Updates the language.detection.count variable.
  *
  * This is used to check if a site is multilingual or not.
  *
  * @see language_multilingual()
  */
 function language_update_count() {
-  variable_set('language_count', db_query('SELECT COUNT(langcode) FROM {language} WHERE locked = 0')->fetchField());
+  state('language.detection')
+    ->set('count', db_query('SELECT COUNT(langcode) FROM {language} WHERE locked = 0')->fetchField())
+    ->save();
 }
 
 /**
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageDependencyInjectionTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageDependencyInjectionTest.php
index f72c51a..4eddc22 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageDependencyInjectionTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageDependencyInjectionTest.php
@@ -71,7 +71,9 @@ function testDependencyInjectedNewDefaultLanguage() {
       'method_id' => 'language-default',
       'default' => TRUE,
     );
-    variable_set('language_default', $new_language_default);
+    config('language.detection')
+      ->set('default', $new_language_default)
+      ->save();
 
     // Initialize the language system.
     drupal_language_initialize();
@@ -83,8 +85,5 @@ function testDependencyInjectedNewDefaultLanguage() {
     foreach ($expected as $property => $value) {
       $this->assertEqual($expected->$property, $result->$property, format_string('The dependency injected language object %prop property equals the default language object %prop property.', array('%prop' => $property)));
     }
-
-    // Delete the language_default variable we previously set.
-    variable_del('language_default');
   }
 }
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php
index 54a5f0e..dfa87a8 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php
@@ -116,10 +116,11 @@ function testLanguageList() {
     // Verify that language is no longer found.
     $this->drupalGet('admin/config/regional/language/delete/' . $langcode);
     $this->assertResponse(404, 'Language no longer found.');
-    // Make sure the "language_count" variable has been updated correctly.
+    // Make sure the "language.settings.count" variable has been updated
+    // correctly.
     drupal_static_reset('language_list');
     $languages = language_list();
-    $this->assertEqual(variable_get('language_count', 1), count($languages), 'Language count is correct.');
+    $this->assertEqual(state('language.detection')->get('count'), count($languages), 'Language count is correct.');
     // Delete French.
     $this->drupalPost('admin/config/regional/language/delete/fr', array(), t('Delete'));
     // Get the count of languages.
@@ -132,8 +133,8 @@ function testLanguageList() {
     // Verify that language is no longer found.
     $this->drupalGet('admin/config/regional/language/delete/fr');
     $this->assertResponse(404, 'Language no longer found.');
-    // Make sure the "language_count" variable has not changed.
-    $this->assertEqual(variable_get('language_count', 1), count($languages), 'Language count is correct.');
+    // Make sure the "language.settings.count" variable has not changed.
+    $this->assertEqual(state('language.detection')->get('count'), count($languages), 'Language count is correct.');
 
     // Ensure we can delete the English language. Right now English is the only
     // language so we must add a new language and make it the default before
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageNegotiationInfoTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageNegotiationInfoTest.php
index 961a556..705cc2a 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageNegotiationInfoTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageNegotiationInfoTest.php
@@ -42,8 +42,12 @@ function setUp() {
    */
   function testInfoAlterations() {
     // Enable language type/negotiation info alterations.
-    variable_set('language_test_language_types', TRUE);
-    variable_set('language_test_language_negotiation_info', TRUE);
+    config('language.test')
+      ->set('types', TRUE)
+      ->save();
+    config('language.test')
+      ->set('negotiation', TRUE)
+      ->save();
     $this->languageNegotiationUpdate();
 
     // Check that fixed language types are properly configured without the need
@@ -52,10 +56,12 @@ function testInfoAlterations() {
 
     // Make the content language type configurable by updating the language
     // negotiation settings with the proper flag enabled.
-    variable_set('language_test_content_language_type', TRUE);
+    config('language.test')
+      ->set('content_type', TRUE)
+      ->save();
     $this->languageNegotiationUpdate();
     $type = LANGUAGE_TYPE_CONTENT;
-    $language_types = variable_get('language_types', language_types_get_default());
+    $language_types = config('language.detection')->get('types') ?: language_types_get_default();
     $this->assertTrue($language_types[$type], 'Content language type is configurable.');
 
     // Enable some core and custom language negotiation methods. The test
@@ -73,7 +79,9 @@ function testInfoAlterations() {
 
     // Remove the interface language negotiation method by updating the language
     // negotiation settings with the proper flag enabled.
-    variable_set('language_test_language_negotiation_info_alter', TRUE);
+    config('language.test')
+      ->set('negotiation_alter', TRUE)
+      ->save();
     $this->languageNegotiationUpdate();
     $negotiation = variable_get("language_negotiation_$type", array());
     $this->assertFalse(isset($negotiation[$interface_method_id]), 'Interface language negotiation method removed from the stored settings.');
@@ -93,7 +101,7 @@ function testInfoAlterations() {
 
     // Check language negotiation results.
     $this->drupalGet('');
-    $last = variable_get('language_test_language_negotiation_last', array());
+    $last = config('language.test')->get('negotiation_last') ?: array();
     foreach (language_types_get_all() as $type) {
       $langcode = $last[$type];
       $value = $type == LANGUAGE_TYPE_CONTENT || strpos($type, 'test') !== FALSE ? 'it' : 'en';
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php
index 66e7007..99e2614 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php
@@ -103,11 +103,22 @@ function testUILanguageNegotiation() {
     // be some bug.
     drupal_static_reset('language_list');
     $languages = language_list();
-    variable_set('language_default', (array) $languages['vi']);
+    $language_settings = config('lanuage.detection');
+    $language_settings
+      ->set('default', (array) $languages['vi'])
+      ->save();
     // First visit this page to make sure our target string is searchable.
     $this->drupalGet('admin/config');
     // Now the t()'ed string is in db so switch the language back to default.
-    variable_del('language_default');
+    $language_settings
+      ->set('default', array(
+        'langcode' => 'en',
+        'name' => 'English',
+        'direction' => 0,
+        'weight' => 0,
+        'locked' => 0
+        ))
+      ->save();
 
     // Translate the string.
     $language_browser_fallback_string = "In $langcode_browser_fallback In $langcode_browser_fallback In $langcode_browser_fallback";
@@ -382,7 +393,9 @@ protected function runTest($test) {
         ->save();
     }
     if (!empty($test['language_test_domain'])) {
-      variable_set('language_test_domain', $test['language_test_domain']);
+      config('language.test')
+        ->set('domain', $test['language_test_domain'])
+        ->save();
     }
     $this->drupalGet($test['path'], array(), $test['http_header']);
     $this->assertText($test['expect'], $test['message']);
diff --git a/core/modules/language/tests/language_test.module b/core/modules/language/tests/language_test.module
index be0a8c0..52dc927 100644
--- a/core/modules/language/tests/language_test.module
+++ b/core/modules/language/tests/language_test.module
@@ -12,7 +12,7 @@
  * the HTTP_HOST here
  */
 function language_test_boot() {
-  if (variable_get('language_test_domain')) {
+  if (config('language.test')->get('domain')) {
     $_SERVER['HTTP_HOST'] = variable_get('language_test_domain');
   }
 }
@@ -31,7 +31,7 @@ function language_test_init() {
  * Implements hook_language_types_info().
  */
 function language_test_language_types_info() {
-  if (variable_get('language_test_language_types', FALSE)) {
+  if (config('language.detection')->get('types')) {
     return array(
       'test_language_type' => array(
         'name' => t('Test'),
@@ -48,7 +48,7 @@ function language_test_language_types_info() {
  * Implements hook_language_types_info_alter().
  */
 function language_test_language_types_info_alter(array &$language_types) {
-  if (variable_get('language_test_content_language_type', FALSE)) {
+  if (config('language.test')->get('content_type')) {
     unset($language_types[LANGUAGE_TYPE_CONTENT]['fixed']);
   }
 }
@@ -57,7 +57,7 @@ function language_test_language_types_info_alter(array &$language_types) {
  * Implements hook_language_negotiation_info().
  */
 function language_test_language_negotiation_info() {
-  if (variable_get('language_test_language_negotiation_info', FALSE)) {
+  if (config('language.test')->get('negotiation_info')) {
     $info = array(
       'callbacks' => array(
         'negotiation' => 'language_test_language_negotiation_method',
@@ -84,7 +84,7 @@ function language_test_language_negotiation_info() {
  * Implements hook_language_negotiation_info_alter().
  */
 function language_test_language_negotiation_info_alter(array &$negotiation_info) {
-  if (variable_get('language_test_language_negotiation_info_alter', FALSE)) {
+  if (config('language.test')->get('negotiation_alter')) {
     unset($negotiation_info[LANGUAGE_NEGOTIATION_INTERFACE]);
   }
 }
@@ -97,7 +97,9 @@ function language_test_store_language_negotiation() {
   foreach (language_types_get_all() as $type) {
     $last[$type] = language($type)->langcode;
   }
-  variable_set('language_test_language_negotiation_last', $last);
+  config('language.test')
+    ->set('negotiation_last', $last)
+    ->save();
 }
 
 /**
diff --git a/core/modules/locale/lib/Drupal/locale/Tests/LocaleUninstallTest.php b/core/modules/locale/lib/Drupal/locale/Tests/LocaleUninstallTest.php
index 06583de..e47942c 100644
--- a/core/modules/locale/lib/Drupal/locale/Tests/LocaleUninstallTest.php
+++ b/core/modules/locale/lib/Drupal/locale/Tests/LocaleUninstallTest.php
@@ -87,7 +87,9 @@ function testUninstallProcess() {
 
     // Change language negotiation options.
     drupal_load('module', 'locale');
-    variable_set('language_types', language_types_get_default() + array('language_custom' => TRUE));
+    config('language.detection')
+      ->set('types', language_types_get_default() + array('language_custom' => TRUE))
+      ->save();
     variable_set('language_negotiation_' . LANGUAGE_TYPE_INTERFACE, language_language_negotiation_info());
     variable_set('language_negotiation_' . LANGUAGE_TYPE_CONTENT, language_language_negotiation_info());
     variable_set('language_negotiation_' . LANGUAGE_TYPE_URL, language_language_negotiation_info());
@@ -114,7 +116,7 @@ function testUninstallProcess() {
     $this->assertTrue($result = !file_exists($js_file), t('JavaScript file deleted: %file', array('%file' => $result ? $js_file : t('found'))));
 
     // Check language count.
-    $language_count = variable_get('language_count', 1);
+    $language_count = state('language.detection')->get('count');
     $this->assertEqual($language_count, 1, t('Language count: %count', array('%count' => $language_count)));
 
     // Check language negotiation.