diff --git a/core/config/schema/core.data_types.schema.yml b/core/config/schema/core.data_types.schema.yml
index 60628fb..b5be2ee 100644
--- a/core/config/schema/core.data_types.schema.yml
+++ b/core/config/schema/core.data_types.schema.yml
@@ -161,12 +161,6 @@ theme_settings:
         node_user_picture:
           type: boolean
           label: 'User pictures in posts'
-        main_menu:
-          type: boolean
-          label: 'Main menu'
-        secondary_menu:
-          type: boolean
-          label: 'Secondary menu'
         slogan:
           type: boolean
           label: 'Site slogan'
diff --git a/core/includes/common.inc b/core/includes/common.inc
index 3d245a0..16136a1 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -2501,20 +2501,6 @@ function drupal_prepare_page($page) {
   \Drupal::moduleHandler()->alter('page', $page);
   \Drupal::theme()->alter('page', $page);
 
-  // The "main" and "secondary" menus are never part of the page-level render
-  // array and therefore their cache tags will never bubble up into the page
-  // cache, even though they should be. This happens because they're rendered
-  // directly by the theme system.
-  // @todo Remove this once https://drupal.org/node/1869476 lands.
-  if (theme_get_setting('features.main_menu') && count(menu_main_menu())) {
-    $main_links_source = _menu_get_links_source('main_links', 'main');
-    $page['page_top']['#cache']['tags']['menu'][$main_links_source] = $main_links_source;
-  }
-  if (theme_get_setting('features.secondary_menu') && count(menu_secondary_menu())) {
-    $secondary_links_source = _menu_get_links_source('secondary_links', 'account');
-    $page['page_top']['#cache']['tags']['menu'][$secondary_links_source] = $secondary_links_source;
-  }
-
   // If no module has taken care of the main content, add it to the page now.
   // This allows the site to still be usable even if no modules that
   // control page regions (for example, the Block module) are enabled.
diff --git a/core/includes/menu.inc b/core/includes/menu.inc
index 51dcd9a..2afdaa9 100644
--- a/core/includes/menu.inc
+++ b/core/includes/menu.inc
@@ -311,23 +311,6 @@
  * Implements template_preprocess_HOOK() for theme_menu_tree().
  */
 function template_preprocess_menu_tree(&$variables) {
-  if (isset($variables['tree']['#heading'])) {
-    $variables['heading'] = $variables['tree']['#heading'];
-    $heading = &$variables['heading'];
-    // Convert a string heading into an array, using a H2 tag by default.
-    if (is_string($heading)) {
-      $heading = array('text' => $heading);
-    }
-    // Merge in default array properties into $heading.
-    $heading += array(
-      'level' => 'h2',
-      'attributes' => array(),
-    );
-    // Convert the attributes array into an Attribute object.
-    $heading['attributes'] = new Attribute($heading['attributes']);
-    $heading['text'] = String::checkPlain($heading['text']);
-  }
-
   if (isset($variables['tree']['#attributes'])) {
     $variables['attributes'] = new Attribute($variables['tree']['#attributes']);
   }
@@ -337,7 +320,6 @@ function template_preprocess_menu_tree(&$variables) {
   if (!isset($variables['attributes']['class'])) {
     $variables['attributes']['class'] = array();
   }
-  $variables['attributes']['class'][] = 'menu';
 
   $variables['tree'] = $variables['tree']['#children'];
 }
@@ -472,72 +454,6 @@ function menu_list_system_menus() {
 }
 
 /**
- * Returns an array of links to be rendered as the Main menu.
- */
-function menu_main_menu() {
-  $main_links_source = _menu_get_links_source('main_links', 'main');
-  return menu_navigation_links($main_links_source);
-}
-
-/**
- * Returns an array of links to be rendered as the Secondary links.
- */
-function menu_secondary_menu() {
-  $main_links_source = _menu_get_links_source('main_links', 'main');
-  $secondary_links_source = _menu_get_links_source('secondary_links', 'account');
-
-  // If the secondary menu source is set as the primary menu, we display the
-  // second level of the primary menu.
-  if ($secondary_links_source == $main_links_source) {
-    return menu_navigation_links($main_links_source, 1);
-  }
-  else {
-    return menu_navigation_links($secondary_links_source, 0);
-  }
-}
-
-/**
- * Returns the source of links of a menu.
- *
- * @param string $name
- *   A string configuration key of menu link source.
- * @param string $default
- *   Default menu name.
- *
- * @return string
- *   Returns menu name, if exist
- */
-function _menu_get_links_source($name, $default) {
-  $config = \Drupal::config('menu_ui.settings');
-  return \Drupal::moduleHandler()->moduleExists('menu_ui') ? $config->get($name) : $default;
-}
-
-/**
- * Builds a renderable array for a navigation menu.
- *
- * @param string $menu_name
- *   The name of the menu.
- * @param int $level
- *   Optional, the depth of the menu to be returned.
- *
- * @return array
- *   A renderable array.
- */
-function menu_navigation_links($menu_name, $level = 0) {
-  $menu_tree = \Drupal::menuTree();
-  $parameters = $menu_tree->getCurrentRouteMenuTreeParameters($menu_name);
-  $parameters->setMaxDepth($level + 1);
-  $tree = $menu_tree->load($menu_name, $parameters);
-  $manipulators = array(
-    array('callable' => 'menu.default_tree_manipulators:checkAccess'),
-    array('callable' => 'menu.default_tree_manipulators:generateIndexAndSort'),
-    array('callable' => 'menu.default_tree_manipulators:extractSubtreeOfActiveTrail', 'args' => array($level)),
-  );
-  $tree = $menu_tree->transform($tree, $manipulators);
-  return $menu_tree->build($tree);
-}
-
-/**
  * Collects the local tasks (tabs), action links, and the root path.
  *
  * @param int $level
diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index b349918..be97369 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -1827,8 +1827,6 @@ function template_preprocess_page(&$variables) {
   $variables['site_slogan']       = (theme_get_setting('features.slogan') ? Xss::filterAdmin($site_config->get('slogan')) : '');
 
   if (!defined('MAINTENANCE_MODE')) {
-    $variables['main_menu']      = theme_get_setting('features.main_menu') ? menu_main_menu() : array();
-    $variables['secondary_menu'] = theme_get_setting('features.secondary_menu') ? menu_secondary_menu() : array();
     $variables['action_links']   = menu_get_local_actions();
     $variables['tabs']           = menu_local_tabs();
 
@@ -1846,33 +1844,11 @@ function template_preprocess_page(&$variables) {
     }
   }
   else {
-    $variables['main_menu']      = array();
-    $variables['secondary_menu'] = array();
     $variables['action_links']   = array();
     $variables['tabs']           = array();
     $variables['feed_icons']     = '';
   }
 
-  // Pass the main menu and secondary menu to the template as render arrays.
-  if (!empty($variables['main_menu'])) {
-    $variables['main_menu']['#heading'] = array(
-      'text' => t('Main menu'),
-      'attributes' => array(
-        'id' => 'links__system_main_menu',
-        'class' => array('visually-hidden'),
-       ),
-    );
-  }
-  if (!empty($variables['secondary_menu'])) {
-    $variables['secondary_menu']['#heading'] = array(
-      'text' => t('Secondary menu'),
-      'attributes' => array(
-        'id' => 'links__system_secondary_menu',
-        'class' => array('visually-hidden'),
-      ),
-    );
-  }
-
   if ($node = \Drupal::routeMatch()->getParameter('node')) {
     $variables['node'] = $node;
   }
diff --git a/core/lib/Drupal/Core/Extension/ThemeHandler.php b/core/lib/Drupal/Core/Extension/ThemeHandler.php
index a4a086a..a02d810 100644
--- a/core/lib/Drupal/Core/Extension/ThemeHandler.php
+++ b/core/lib/Drupal/Core/Extension/ThemeHandler.php
@@ -34,8 +34,6 @@ class ThemeHandler implements ThemeHandlerInterface {
     'node_user_picture',
     'comment_user_picture',
     'comment_user_verification',
-    'main_menu',
-    'secondary_menu',
   );
 
   /**
diff --git a/core/lib/Drupal/Core/Menu/DefaultMenuLinkTreeManipulators.php b/core/lib/Drupal/Core/Menu/DefaultMenuLinkTreeManipulators.php
index 0d6c995..29fa9bc 100644
--- a/core/lib/Drupal/Core/Menu/DefaultMenuLinkTreeManipulators.php
+++ b/core/lib/Drupal/Core/Menu/DefaultMenuLinkTreeManipulators.php
@@ -234,31 +234,4 @@ public function flatten(array $tree) {
     return $tree;
   }
 
-  /**
-   * Extracts a subtree of the active trail.
-   *
-   * @param \Drupal\Core\Menu\MenuLinkTreeElement[] $tree
-   *   The menu link tree to manipulate.
-   * @param int $level
-   *   The level in the active trail to extract.
-   *
-   * @return \Drupal\Core\Menu\MenuLinkTreeElement[]
-   *   The manipulated menu link tree.
-   */
-  public function extractSubtreeOfActiveTrail(array $tree, $level) {
-    // Go down the active trail until the right level is reached.
-    while ($level-- > 0 && $tree) {
-      // Loop through the current level's elements  until we find one that is in
-      // the active trail.
-      while ($element = array_shift($tree)) {
-        if ($element->inActiveTrail) {
-          // If the element is in the active trail, we continue in the subtree.
-          $tree = $element->subtree;
-          break;
-        }
-      }
-    }
-    return $tree;
-  }
-
 }
diff --git a/core/modules/block/block.module b/core/modules/block/block.module
index 339d163..9582874 100644
--- a/core/modules/block/block.module
+++ b/core/modules/block/block.module
@@ -267,6 +267,7 @@ function template_preprocess_block(&$variables) {
   $variables['base_plugin_id'] = $variables['elements']['#base_plugin_id'];
   $variables['derivative_plugin_id'] = $variables['elements']['#derivative_plugin_id'];
   $variables['label'] = !empty($variables['configuration']['label_display']) ? $variables['configuration']['label'] : '';
+  $variables['label_display'] = $variables['configuration']['label_display'];
   $variables['content'] = $variables['elements']['content'];
   // A block's label is configuration: it is static. Allow dynamic labels to be
   // set in the render array.
diff --git a/core/modules/menu_ui/config/install/menu_ui.settings.yml b/core/modules/menu_ui/config/install/menu_ui.settings.yml
index a79ac97..c3ee6fb 100644
--- a/core/modules/menu_ui/config/install/menu_ui.settings.yml
+++ b/core/modules/menu_ui/config/install/menu_ui.settings.yml
@@ -1,3 +1 @@
-main_links: main
-secondary_links: account
 override_parent_selector: false
diff --git a/core/modules/menu_ui/config/schema/menu_ui.schema.yml b/core/modules/menu_ui/config/schema/menu_ui.schema.yml
index 7855ba3..ed1fef8 100644
--- a/core/modules/menu_ui/config/schema/menu_ui.schema.yml
+++ b/core/modules/menu_ui/config/schema/menu_ui.schema.yml
@@ -4,12 +4,6 @@ menu_ui.settings:
   type: mapping
   label: 'Menu settings'
   mapping:
-    main_links:
-      type: string
-      label: 'Main links'
-    secondary_links:
-      type: string
-      label: 'Source for secondary links'
     override_parent_selector:
       type: boolean
       label: 'Override parent selector'
diff --git a/core/modules/menu_ui/menu_ui.links.task.yml b/core/modules/menu_ui/menu_ui.links.task.yml
index d9f1937..10dd8d0 100644
--- a/core/modules/menu_ui/menu_ui.links.task.yml
+++ b/core/modules/menu_ui/menu_ui.links.task.yml
@@ -7,9 +7,3 @@ menu_ui.overview_page:
   title: 'List'
   route_name: menu_ui.overview_page
   base_route: menu_ui.overview_page
-
-menu_ui.settings:
-  title: 'Settings'
-  route_name: menu_ui.settings
-  base_route: menu_ui.overview_page
-  weight: 100
diff --git a/core/modules/menu_ui/menu_ui.routing.yml b/core/modules/menu_ui/menu_ui.routing.yml
index 1b431e9..97fd744 100644
--- a/core/modules/menu_ui/menu_ui.routing.yml
+++ b/core/modules/menu_ui/menu_ui.routing.yml
@@ -1,11 +1,3 @@
-menu_ui.settings:
-  path: '/admin/structure/menu/settings'
-  defaults:
-    _form: 'Drupal\menu_ui\MenuSettingsForm'
-    _title: 'Menus'
-  requirements:
-    _permission: 'administer menu'
-
 menu_ui.overview_page:
   path: '/admin/structure/menu'
   defaults:
diff --git a/core/modules/menu_ui/src/MenuSettingsForm.php b/core/modules/menu_ui/src/MenuSettingsForm.php
deleted file mode 100644
index 9037bb5..0000000
--- a/core/modules/menu_ui/src/MenuSettingsForm.php
+++ /dev/null
@@ -1,73 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\menu_ui\MenuSettingsForm.
- */
-
-namespace Drupal\menu_ui;
-
-use Drupal\Core\Form\ConfigFormBase;
-use Drupal\Core\Form\FormStateInterface;
-
-/**
- * Select the menus to be used for the main and secondary links for this site.
- */
-class MenuSettingsForm extends ConfigFormBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getFormId() {
-    return 'menu_configure';
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function buildForm(array $form, FormStateInterface $form_state) {
-    $config = $this->config('menu_ui.settings');
-    $form['intro'] = array(
-      '#type' => 'item',
-      '#markup' => t('The Menu UI module allows on-the-fly creation of menu links in the content authoring forms. To configure these settings for a particular content type, visit the <a href="@content-types">Content types</a> page, click the <em>edit</em> link for the content type, and go to the <em>Menu settings</em> section.', array('@content-types' => url('admin/structure/types'))),
-    );
-
-    $menu_options = menu_ui_get_menus();
-
-    $main = $config->get('main_links');
-    $form['menu_main_links_source'] = array(
-      '#type' => 'select',
-      '#title' => t('Source for the Main links'),
-      '#default_value' => $main,
-      '#empty_option' => t('No Main links'),
-      '#options' => $menu_options,
-      '#tree' => FALSE,
-      '#description' => t('Select what should be displayed as the Main links (typically at the top of the page).'),
-    );
-
-    $form['menu_secondary_links_source'] = array(
-      '#type' => 'select',
-      '#title' => t('Source for the Secondary links'),
-      '#default_value' => $config->get('secondary_links'),
-      '#empty_option' => t('No Secondary links'),
-      '#options' => $menu_options,
-      '#tree' => FALSE,
-      '#description' => t('Select the source for the Secondary links. An advanced option allows you to use the same source for both Main links (currently %main) and Secondary links: if your source menu has two levels of hierarchy, the top level menu links will appear in the Main links, and the children of the active link will appear in the Secondary links.', array('%main' => $main ? $menu_options[$main] : t('none'))),
-    );
-
-    return parent::buildForm($form, $form_state);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function submitForm(array &$form, FormStateInterface $form_state) {
-    $this->config('menu_ui.settings')
-      ->set('main_links', $form_state->getValue('menu_main_links_source'))
-      ->set('secondary_links', $form_state->getValue('menu_secondary_links_source'))
-      ->save();
-
-    parent::submitForm($form, $form_state);
-  }
-
-}
diff --git a/core/modules/menu_ui/src/Tests/MenuNodeTest.php b/core/modules/menu_ui/src/Tests/MenuNodeTest.php
index 11a1aca..fdd0e71 100644
--- a/core/modules/menu_ui/src/Tests/MenuNodeTest.php
+++ b/core/modules/menu_ui/src/Tests/MenuNodeTest.php
@@ -22,10 +22,13 @@ class MenuNodeTest extends WebTestBase {
    *
    * @var array
    */
-  public static $modules = array('menu_ui', 'test_page_test', 'node');
+  public static $modules = array('menu_ui', 'test_page_test', 'node', 'block');
 
   protected function setUp() {
     parent::setUp();
+
+    $this->drupalPlaceBlock('system_menu_block:main');
+
     $this->drupalCreateContentType(array('type' => 'page', 'name' => 'Basic page'));
 
     $this->admin_user = $this->drupalCreateUser(array(
diff --git a/core/modules/menu_ui/src/Tests/MenuTest.php b/core/modules/menu_ui/src/Tests/MenuTest.php
index 09bc6f4..c35d0d1 100644
--- a/core/modules/menu_ui/src/Tests/MenuTest.php
+++ b/core/modules/menu_ui/src/Tests/MenuTest.php
@@ -839,13 +839,6 @@ private function verifyAccess($response = 200) {
       $this->assertText(t('Edit menu item'), 'Menu edit page was displayed');
     }
 
-    // View menu settings page.
-    $this->drupalGet('admin/structure/menu/settings');
-    $this->assertResponse($response);
-    if ($response == 200) {
-      $this->assertText(t('Menus'), 'Menu settings page was displayed');
-    }
-
     // View add menu page.
     $this->drupalGet('admin/structure/menu/add');
     $this->assertResponse($response);
diff --git a/core/modules/migrate_drupal/src/Tests/Dump/Drupal6MenuSettings.php b/core/modules/migrate_drupal/src/Tests/Dump/Drupal6MenuSettings.php
index 752614a..a5ac43f 100644
--- a/core/modules/migrate_drupal/src/Tests/Dump/Drupal6MenuSettings.php
+++ b/core/modules/migrate_drupal/src/Tests/Dump/Drupal6MenuSettings.php
@@ -23,14 +23,6 @@ public function load() {
       'value',
     ))
     ->values(array(
-      'name' => 'menu_primary_links_source',
-      'value' => 's:13:"primary-links";',
-    ))
-    ->values(array(
-      'name' => 'menu_secondary_links_source',
-      'value' => 's:15:"secondary-links";',
-    ))
-    ->values(array(
       'name' => 'menu_override_parent_selector',
       'value' => 'b:0;',
     ))
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateMenuConfigsTest.php b/core/modules/migrate_drupal/src/Tests/d6/MigrateMenuConfigsTest.php
index aa4fd0c..cc8a89d 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateMenuConfigsTest.php
+++ b/core/modules/migrate_drupal/src/Tests/d6/MigrateMenuConfigsTest.php
@@ -46,8 +46,6 @@ protected function setUp() {
    */
   public function testMenuSettings() {
     $config = \Drupal::config('menu_ui.settings');
-    $this->assertIdentical($config->get('main_links'), 'primary-links');
-    $this->assertIdentical($config->get('secondary_links'), 'secondary-links');
     $this->assertIdentical($config->get('override_parent_selector'), FALSE);
     $this->assertConfigSchema(\Drupal::service('config.typed'), 'menu_ui.settings', $config->get());
   }
diff --git a/core/modules/system/config/install/system.theme.global.yml b/core/modules/system/config/install/system.theme.global.yml
index 13036bf..5ee6cc7 100644
--- a/core/modules/system/config/install/system.theme.global.yml
+++ b/core/modules/system/config/install/system.theme.global.yml
@@ -10,8 +10,6 @@ features:
   logo: true
   name: true
   node_user_picture: true
-  main_menu: true
-  secondary_menu: true
   slogan: true
 logo:
   path: ''
diff --git a/core/modules/system/src/Form/ThemeSettingsForm.php b/core/modules/system/src/Form/ThemeSettingsForm.php
index b65628a..c790c79 100644
--- a/core/modules/system/src/Form/ThemeSettingsForm.php
+++ b/core/modules/system/src/Form/ThemeSettingsForm.php
@@ -106,8 +106,6 @@ public function buildForm(array $form, FormStateInterface $form_state, $theme =
       'comment_user_picture' => t('User pictures in comments'),
       'comment_user_verification' => t('User verification status in comments'),
       'favicon' => t('Shortcut icon'),
-      'main_menu' => t('Main menu'),
-      'secondary_menu' => t('Secondary menu'),
     );
 
     // Some features are not always available
diff --git a/core/modules/system/src/Tests/Cache/PageCacheTagsIntegrationTest.php b/core/modules/system/src/Tests/Cache/PageCacheTagsIntegrationTest.php
index 9c41eb8..ba0d8cc 100644
--- a/core/modules/system/src/Tests/Cache/PageCacheTagsIntegrationTest.php
+++ b/core/modules/system/src/Tests/Cache/PageCacheTagsIntegrationTest.php
@@ -77,7 +77,11 @@ function testPageCacheTags() {
       'block:bartik_login',
       'block:bartik_footer',
       'block:bartik_powered',
+      'block:bartik_mainnavigation_level1',
+      'block:bartik_useraccountmenu_level1',
       'block_plugin:system_main_block',
+      'block_plugin:system_menu_block__account',
+      'block_plugin:system_menu_block__main',
       'block_plugin:system_menu_block__tools',
       'block_plugin:user_login_block',
       'block_plugin:system_menu_block__footer',
@@ -86,6 +90,7 @@ function testPageCacheTags() {
       'node:' . $node_1->id(),
       'user:' . $author_1->id(),
       'filter_format:basic_html',
+      'menu:account',
       'menu:tools',
       'menu:footer',
       'menu:main',
@@ -103,7 +108,11 @@ function testPageCacheTags() {
       'block:' . $block->id(),
       'block:bartik_footer',
       'block:bartik_powered',
+      'block:bartik_mainnavigation_level1',
+      'block:bartik_useraccountmenu_level1',
       'block_plugin:system_main_block',
+      'block_plugin:system_menu_block__account',
+      'block_plugin:system_menu_block__main',
       'block_plugin:system_menu_block__tools',
       'block_plugin:user_login_block',
       'block_plugin:views_block__comments_recent-block_1',
@@ -113,6 +122,7 @@ function testPageCacheTags() {
       'node:' . $node_2->id(),
       'user:' . $author_2->id(),
       'filter_format:full_html',
+      'menu:account',
       'menu:tools',
       'menu:footer',
       'menu:main',
diff --git a/core/modules/system/src/Tests/System/PageTitleTest.php b/core/modules/system/src/Tests/System/PageTitleTest.php
index 6b2d249..4516a57 100644
--- a/core/modules/system/src/Tests/System/PageTitleTest.php
+++ b/core/modules/system/src/Tests/System/PageTitleTest.php
@@ -75,8 +75,6 @@ function testTitleXSS() {
     $edit = array(
       'toggle_name'           => TRUE,
       'toggle_slogan'         => TRUE,
-      'toggle_main_menu'      => TRUE,
-      'toggle_secondary_menu' => TRUE,
     );
     $this->drupalPostForm('admin/appearance/settings', $edit, t('Save configuration'));
 
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index f3b65a2..6142dfc 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -154,13 +154,16 @@ function system_help($route_name, RouteMatchInterface $route_match) {
 function system_theme() {
   return array_merge(drupal_common_theme(), array(
     // Normally theme suggestion templates are only picked up when they are in
-    // themes. We explicitly define the block__system_branding_block theme
-    // suggestion here so that the template in core/modules/system/templates
-    // is picked up.
+    // themes. We explicitly define theme suggestions here so that the block
+    // templates in core/modules/system/templates are picked up.
     'block__system_branding_block' => array(
       'base hook' => 'block',
       'template' => 'block--system-branding-block',
     ),
+    'block__system_menu_block' => array(
+      'base hook' => 'block',
+      'template' => 'block--system-menu-block',
+    ),
     'system_themes_page' => array(
       'variables' => array(
         'theme_groups' => array(),
@@ -712,14 +715,6 @@ function system_preprocess_block(&$variables) {
     case 'system_help_block':
       $variables['attributes']['role'] = 'complementary';
       break;
-
-    case 'system_menu_block':
-      $menus = menu_list_system_menus();
-      if (isset($menus[$variables['derivative_plugin_id']])) {
-        $variables['attributes']['role'] = 'navigation';
-        $variables['attributes']['class'][] = 'block-menu';
-      }
-      break;
   }
 }
 
@@ -967,8 +962,6 @@ function _system_default_theme_features() {
     'node_user_picture',
     'comment_user_picture',
     'comment_user_verification',
-    'main_menu',
-    'secondary_menu',
   );
 }
 
diff --git a/core/modules/system/templates/block--system-menu-block.html.twig b/core/modules/system/templates/block--system-menu-block.html.twig
new file mode 100644
index 0000000..acadc15
--- /dev/null
+++ b/core/modules/system/templates/block--system-menu-block.html.twig
@@ -0,0 +1,48 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a menu block.
+ *
+ * Available variables:
+ * - …
+ *
+ * Headings should be used on navigation menus that consistently appears on
+ * multiple pages. When this menu block's label is configured to not be
+ * displayed, it is automatically made invisible using the 'visually-hidden' CSS
+ * class, which still keeps it visible for screen-readers and assistive
+ * technology. Headings allow screen-reader and keyboard only users to navigate
+ * to or skip the links.
+ * See http://juicystudio.com/article/screen-readers-display-none.php and
+ * http://www.w3.org/TR/WCAG-TECHS/H42.html for more information.
+ *
+ * @ingroup themeable
+ */
+#}
+{%
+  set classes = [
+    'block',
+    'block-menu',
+    'navigation',
+  ]
+%}
+{% set heading_id = attributes.id ~ '-menu'|clean_id %}
+<nav{{ attributes.addClass(classes) }} role="navigation" aria-labelledby="{{ heading_id }}">
+  {# Block title. If not displayed, we still provide it for screen readers. #}
+  {% if not label_display %}
+    {% set title_attributes = title_attributes.addClass(['visually-hidden']) %}
+  {% endif %}
+  {{ title_prefix }}
+    <h2 id="{{ heading_id }}"{{ title_attributes }}>{{ configuration.label }}</h2>
+  {{ title_suffix }}
+
+  {# Menu #}
+  {% if label_display %}
+    <div{{ content_attributes.addClass('content') }}>
+  {% endif %}
+    {% block content %}
+      {{ content }}
+    {% endblock %}
+  {% if label_display %}
+    </div>
+  {% endif %}
+</nav>
diff --git a/core/modules/system/templates/menu-tree.html.twig b/core/modules/system/templates/menu-tree.html.twig
index 03acca6..82a3d01 100644
--- a/core/modules/system/templates/menu-tree.html.twig
+++ b/core/modules/system/templates/menu-tree.html.twig
@@ -6,20 +6,6 @@
  * Available variables:
  * - attributes: Attributes for the UL containing the tree of links.
  * - tree: Menu tree to be output.
- * - heading: (optional) A heading to precede the links.
- *   - text: The heading text.
- *   - level: The heading level (e.g. 'h2', 'h3').
- *   - attributes: (optional) A keyed list of attributes for the heading.
- *   If the heading is a string, it will be used as the text of the heading and
- *   the level will default to 'h2'.
- *
- *   Headings should be used on navigation menus and any list of links that
- *   consistently appears on multiple pages. To make the heading invisible use
- *   the 'visually-hidden' CSS class. Do not use 'display:none', which
- *   removes it from screen-readers and assistive technology. Headings allow
- *   screen-reader and keyboard only users to navigate to or skip the links.
- *   See http://juicystudio.com/article/screen-readers-display-none.php and
- *   http://www.w3.org/TR/WCAG-TECHS/H42.html for more information.
  *
  * @see template_preprocess_menu_tree()
  *
@@ -27,14 +13,7 @@
  */
 #}
 {% if tree -%}
-  {%- if heading -%}
-    {%- if heading.level -%}
-      <{{ heading.level }}{{ heading.attributes }}>{{ heading.text }}</{{ heading.level }}>
-    {%- else -%}
-      <h2{{ heading.attributes }}>{{ heading.text }}</h2>
-    {%- endif -%}
-  {%- endif -%}
-  <ul{{ attributes }}>
+  <ul{{ attributes.addClass('menu') }}>
     {{ tree }}
   </ul>
 {%- endif %}
diff --git a/core/modules/system/templates/page.html.twig b/core/modules/system/templates/page.html.twig
index ba013a2..430f860 100644
--- a/core/modules/system/templates/page.html.twig
+++ b/core/modules/system/templates/page.html.twig
@@ -26,9 +26,6 @@
  *   slogan has been disabled in theme settings.
  *
  * Navigation:
- * - main_menu: The Main menu links for the site, if they have been configured.
- * - secondary_menu: The Secondary menu links for the site, if they have been
- *   configured.
  * - breadcrumb: The breadcrumb trail for the current page.
  *
  * Page content (in order of occurrence in the default page.html.twig):
@@ -95,12 +92,14 @@
     {{ page.header }}
   </header>
 
+{# @todo Figure out how to replace this.
   {% if main_menu or secondary_menu %}
     <nav role="navigation" aria-labelledby="links__system_main_menu">
       {{ main_menu }}
       {{ secondary_menu }}
     </nav>
   {% endif %}
+#}
 
   {{ breadcrumb }}
 
diff --git a/core/modules/user/src/Tests/UserAccountLinksTests.php b/core/modules/user/src/Tests/UserAccountLinksTests.php
index 4ad246b..97fa8a3 100644
--- a/core/modules/user/src/Tests/UserAccountLinksTests.php
+++ b/core/modules/user/src/Tests/UserAccountLinksTests.php
@@ -24,8 +24,12 @@ class UserAccountLinksTests extends WebTestBase {
    */
   public static $modules = array('menu_ui', 'block', 'test_page_test');
 
+  /**
+   * {@inheritdoc}
+   */
   protected function setUp() {
     parent::setUp();
+    $this->drupalPlaceBlock('system_menu_block:account');
     // Make test-page default.
     \Drupal::config('system.site')->set('page.front', 'test-page')->save();
   }
diff --git a/core/modules/user/src/Tests/UserPasswordResetTest.php b/core/modules/user/src/Tests/UserPasswordResetTest.php
index 0ea06c0..2e61de5 100644
--- a/core/modules/user/src/Tests/UserPasswordResetTest.php
+++ b/core/modules/user/src/Tests/UserPasswordResetTest.php
@@ -22,9 +22,21 @@ class UserPasswordResetTest extends WebTestBase {
    */
   protected $account;
 
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = ['block'];
+
+  /**
+   * {@inheritdoc}
+   */
   protected function setUp() {
     parent::setUp();
 
+    $this->drupalPlaceBlock('system_menu_block:account');
+
     // Create a user.
     $account = $this->drupalCreateUser();
 
diff --git a/core/modules/views/src/Tests/Wizard/MenuTest.php b/core/modules/views/src/Tests/Wizard/MenuTest.php
index 505b4ce..ba3aa42 100644
--- a/core/modules/views/src/Tests/Wizard/MenuTest.php
+++ b/core/modules/views/src/Tests/Wizard/MenuTest.php
@@ -20,6 +20,8 @@ class MenuTest extends WizardTestBase {
    * Tests the menu functionality.
    */
   function testMenus() {
+    $this->drupalPlaceBlock('system_menu_block:main');
+
     // Create a view with a page display and a menu link in the Main Menu.
     $view = array();
     $view['label'] = $this->randomMachineName(16);
diff --git a/core/profiles/standard/config/install/block.block.bartik_mainnavigation_level1.yml b/core/profiles/standard/config/install/block.block.bartik_mainnavigation_level1.yml
new file mode 100644
index 0000000..eb4b1dc
--- /dev/null
+++ b/core/profiles/standard/config/install/block.block.bartik_mainnavigation_level1.yml
@@ -0,0 +1,25 @@
+id: bartik_mainnavigation_level1
+theme: bartik
+weight: 0
+status: true
+langcode: en
+region: header
+plugin: 'system_menu_block:main'
+settings:
+  visibility: {}
+  id: 'system_menu_block:main'
+  label: 'Main navigation'
+  provider: system
+  label_display: '0'
+  cache:
+    max_age: -1
+    contexts: {  }
+  level: 1
+  depth: 1
+dependencies:
+  entity:
+    - system.menu.main
+  module:
+    - system
+  theme:
+    - bartik
diff --git a/core/profiles/standard/config/install/block.block.bartik_useraccountmenu_level1.yml b/core/profiles/standard/config/install/block.block.bartik_useraccountmenu_level1.yml
new file mode 100644
index 0000000..3c91b29
--- /dev/null
+++ b/core/profiles/standard/config/install/block.block.bartik_useraccountmenu_level1.yml
@@ -0,0 +1,25 @@
+id: bartik_useraccountmenu_level1
+theme: bartik
+weight: 0
+status: true
+langcode: en
+region: header
+plugin: 'system_menu_block:account'
+settings:
+  visibility: { }
+  id: 'system_menu_block:account'
+  label: 'User account menu (level 1)'
+  provider: system
+  label_display: '0'
+  cache:
+    max_age: -1
+    contexts: {  }
+  level: 1
+  depth: 1
+dependencies:
+  entity:
+    - system.menu.account
+  module:
+    - system
+  theme:
+    - bartik
diff --git a/core/tests/Drupal/Tests/Core/Menu/DefaultMenuLinkTreeManipulatorsTest.php b/core/tests/Drupal/Tests/Core/Menu/DefaultMenuLinkTreeManipulatorsTest.php
index cbd81f5..2d3fa4c 100644
--- a/core/tests/Drupal/Tests/Core/Menu/DefaultMenuLinkTreeManipulatorsTest.php
+++ b/core/tests/Drupal/Tests/Core/Menu/DefaultMenuLinkTreeManipulatorsTest.php
@@ -227,65 +227,6 @@ public function testFlatten() {
   }
 
   /**
-   * Tests the extractSubtreeOfActiveTrail() tree manipulator.
-   *
-   * @covers ::extractSubtreeOfActiveTrail
-   */
-  public function testExtractSubtreeOfActiveTrail() {
-    // No link in the active trail.
-    $this->mockTree();
-    // Get level 0.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 0);
-    $this->assertEquals(array(1, 2, 5, 6, 8), array_keys($tree));
-    // Get level 1.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 1);
-    $this->assertEquals(array(), array_keys($tree));
-    // Get level 2.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 1);
-    $this->assertEquals(array(), array_keys($tree));
-
-    // Link 5 in the active trail.
-    $this->mockTree();
-    $this->originalTree[5]->inActiveTrail = TRUE;
-    // Get level 0.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 0);
-    $this->assertEquals(array(1, 2, 5, 6, 8), array_keys($tree));
-    // Get level 1.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 1);
-    $this->assertEquals(array(7), array_keys($tree));
-    // Get level 2.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 2);
-    $this->assertEquals(array(), array_keys($tree));
-
-    // Link 2 in the active trail.
-    $this->mockTree();
-    $this->originalTree[2]->inActiveTrail = TRUE;
-    // Get level 0.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 0);
-    $this->assertEquals(array(1, 2, 5, 6, 8), array_keys($tree));
-    // Get level 1.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 1);
-    $this->assertEquals(array(3), array_keys($tree));
-    // Get level 2.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 2);
-    $this->assertEquals(array(), array_keys($tree));
-
-    // Links 2 and 3 in the active trail.
-    $this->mockTree();
-    $this->originalTree[2]->inActiveTrail = TRUE;
-    $this->originalTree[2]->subtree[3]->inActiveTrail = TRUE;
-    // Get level 0.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 0);
-    $this->assertEquals(array(1, 2, 5, 6, 8), array_keys($tree));
-    // Get level 1.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 1);
-    $this->assertEquals(array(3), array_keys($tree));
-    // Get level 2.
-    $tree = $this->defaultMenuTreeManipulators->extractSubtreeOfActiveTrail($this->originalTree, 2);
-    $this->assertEquals(array(4), array_keys($tree));
-  }
-
-  /**
    * Tests the optimized node access checking.
    *
    * @covers ::checkNodeAccess
diff --git a/core/themes/bartik/bartik.theme b/core/themes/bartik/bartik.theme
index 27f8973..c402cf9 100644
--- a/core/themes/bartik/bartik.theme
+++ b/core/themes/bartik/bartik.theme
@@ -55,17 +55,6 @@ function bartik_preprocess_page(&$variables) {
   // Store back the classes to the htmlpage object.
   $attributes['class'] = $classes;
 
-  // Set additional attributes on the primary and secondary navigation menus.
-  if (!empty($variables['main_menu'])) {
-    $variables['main_menu']['#attributes']['id'] = 'main-menu-links';
-    $variables['main_menu']['#attributes']['class'][] = 'links';
-  }
-  if (!empty($variables['secondary_menu'])) {
-    $variables['secondary_menu']['#attributes']['id'] = 'secondary-menu-links';
-    $variables['secondary_menu']['#attributes']['class'][] = 'links';
-    $variables['secondary_menu']['#attributes']['class'][] = 'inline';
-  }
-
   // Set the options that apply to both page and maintenance page.
   _bartik_process_page($variables);
 
diff --git a/core/themes/bartik/css/colors.css b/core/themes/bartik/css/colors.css
index b52e01e..92f604f 100644
--- a/core/themes/bartik/css/colors.css
+++ b/core/themes/bartik/css/colors.css
@@ -8,8 +8,8 @@ body {
 }
 #page,
 #main-wrapper,
-#main-menu-links li a.active,
-#main-menu-links li.active-trail a {
+#header .block-menu:first-child .menu li a.active,
+#header .block-menu:first-child .menu li.active-trail a {
   background: #ffffff;
 }
 .tabs ul.primary li a.active {
diff --git a/core/themes/bartik/css/layout.css b/core/themes/bartik/css/layout.css
index 7374a10..68826b0 100644
--- a/core/themes/bartik/css/layout.css
+++ b/core/themes/bartik/css/layout.css
@@ -24,14 +24,6 @@ body,
 #header div.section {
   position: relative;
 }
-.region-header {
-  float: right; /* LTR */
-  margin: .5em 5px .75em;
-  border: 1px solid #ccc;
-}
-[dir="rtl"] .region-header {
-  float: left;
-}
 #secondary-menu {
   width: 100%;
   margin: 0 auto;
diff --git a/core/themes/bartik/css/style.css b/core/themes/bartik/css/style.css
index 6470a33..29ecdc4 100644
--- a/core/themes/bartik/css/style.css
+++ b/core/themes/bartik/css/style.css
@@ -420,6 +420,12 @@ h1.site-name {
   list-style-image: none;
   padding: 0;
 }
+/* Treat menu blocks in the region header as a special case. */
+.region-header .block-menu {
+  float: none;
+  margin: 0;
+  font-size: inherit;
+}
 .region-header .form-text {
   background: #fefefe;
   background: rgba(255, 255, 255, 0.7);
@@ -441,30 +447,6 @@ h1.site-name {
 .region-header .form-required:after {
   background-image: url(../images/required.svg);
 }
-/* Region header block menus. */
-.region-header .block-menu {
-  border: 1px solid;
-  border-color: #eee;
-  border-color: rgba(255, 255, 255, 0.2);
-  padding: 0;
-  width: 208px;
-}
-.region-header .block-menu li a {
-  display: block;
-  border-bottom: 1px solid;
-  border-bottom-color: #eee;
-  border-bottom-color: rgba(255, 255, 255, 0.2);
-  padding: 3px 7px;
-}
-.region-header .block-menu li a:hover,
-.region-header .block-menu li a:active,
-.region-header .block-menu li a:focus {
-  text-decoration: none;
-  background: rgba(255, 255, 255, 0.15);
-}
-.region-header .block-menu li:last-child a {
-  border-bottom: 0;
-}
 /* User Login block in the header region */
 .region-header #block-user-login {
   width: auto;
@@ -547,19 +529,19 @@ h1.site-name {
 }
 
 /* --------------- Main Menu ------------ */
-#main-menu {
+#header .block-menu:first-child {
   clear: both;
 }
-#main-menu-links {
+#header .block-menu:first-child .menu {
   font-size: 0.929em;
   margin: 0 5px;
   padding: 0;
   text-align: left; /* LTR */
 }
-[dir="rtl"] #main-menu-links {
+[dir="rtl"] #header .block-menu:first-child .menu {
   text-align: right;
 }
-#main-menu-links li {
+#header .block-menu:first-child .menu li {
   float: none;
   list-style: none;
   margin: 0;
@@ -567,7 +549,7 @@ h1.site-name {
   height: auto;
   width: 100%;
 }
-#main-menu-links a {
+#header .block-menu:first-child .menu a {
   color: #333;
   background: #ccc;
   background: rgba(255, 255, 255, 0.7);
@@ -579,31 +561,38 @@ h1.site-name {
   margin: 4px 0;
   padding: 0.9em 0 0.9em 10px; /* LTR */
 }
-[dir="rtl"] #main-menu-links a {
+[dir="rtl"] #header .block-menu:first-child .menu a {
   padding: 0.9em 10px 0.9em 0;
 }
-#main-menu-links a:hover,
-#main-menu-links a:focus {
+#header .block-menu:first-child .menu a:hover,
+#header .block-menu:first-child .menu a:focus {
   background: #f6f6f2;
   background: rgba(255, 255, 255, 0.95);
 }
-#main-menu-links a:active {
+#header .block-menu:first-child .menu a:active {
   background: #b3b3b3;
   background: rgba(255, 255, 255, 1);
 }
-#main-menu-links li a.active {
+#header .block-menu:first-child .menu li a.active {
   border-bottom: none;
 }
 
 /* ---------- Main Menu Toggle ----------- */
-#nav, #no-nav {
+/* Hide the toggle by default. */
+#header .block-menu .menu-toggle,
+#header .block-menu .menu-toggle-target {
+  display: none;
+}
+/* Unhide it for the main menu. */
+#header .block-menu:first-child .menu-toggle-target {
+  display: inherit;
   position: fixed;
   top: 0;
 }
-.main-menu-reveal {
+#header .block-menu:first-child .menu-toggle {
   display: none;
 }
-body:not(:target) .main-menu-reveal {
+body:not(:target) #header .block-menu:first-child .menu-toggle {
   color: #333;
   background: #ccc;
   background: rgba(255, 255, 255, 0.7);
@@ -615,7 +604,7 @@ body:not(:target) .main-menu-reveal {
   padding: 0.9em 10px 0.9em 10px;
   z-index: 1000;
 }
-body:not(:target) .main-menu-reveal:after {
+body:not(:target) #header .block-menu:first-child .menu-toggle:after {
   content:"";
   background: url(../../../misc/icons/ffffff/hamburger.svg) no-repeat;
   background-size: contain;
@@ -625,21 +614,21 @@ body:not(:target) .main-menu-reveal:after {
   position: absolute;
   right: 10px; /* LTR */
 }
-body:not(:target) #nav:target ~ .main-menu-reveal,
-body:not(:target) .main-menu-reveal--hide {
+body:not(:target) #header .block-menu:first-child .menu-toggle-target-show:target ~ .menu-toggle,
+body:not(:target) #header .block-menu:first-child .menu-toggle--hide {
   display: none;
 }
-body:not(:target) #nav:target ~ .main-menu-reveal--hide {
+body:not(:target) #header .block-menu:first-child .menu-toggle-target-show:target ~ .menu-toggle--hide {
   display: block;
 }
-[dir="rtl"] #secondary-menu-links {
+[dir="rtl"] #header .block-menu:nt-child(2) {
   left: 10px;
   right: auto;
 }
-#main-menu-links .menu-hide a {
+#header .block-menu:first-child .menu .menu-hide a {
   display: none;
 }
-body:not(:target) #nav:target ~ #main-menu-links .menu-hide a {
+body:not(:target) #header .block-menu:first-child .menu-toggle-target-show:target ~ .menu .menu-hide a {
   background-color: transparent;
   border: none;
   display: block;
@@ -652,35 +641,46 @@ body:not(:target) #nav:target ~ #main-menu-links .menu-hide a {
   text-indent: -999em;
   z-index: 1001;
 }
-body:not(:target) #main-menu-links li {
+body:not(:target) #header .block-menu:first-child .menu li {
   height: 0;
   overflow: hidden;
 }
-body:not(:target) #nav:target ~ #main-menu-links li {
+body:not(:target) #header .block-menu:first-child .menu-toggle-target-show:target ~ .menu li {
   height: auto;
   overflow: visible;
 }
 
 /* --------------- Secondary Menu ------------ */
-
-#secondary-menu-links {
+#header .block-menu:nth-child(2) {
+    border: 1px solid red;
+    position: absolute;
+    top: 0;
+    right: 0; /* LTR */
+}
+[dir="rtl"] #header .block-menu:nth-child(2) {
+  right: inherit;
+  left: 0;
+}
+#header .block-menu:nth-child(2) .menu {
   float: right; /* LTR */
+  right: 0; /* LTR */
   font-size: 0.929em;
   margin: 0 10px;
 }
-[dir="rtl"] #secondary-menu-links {
+[dir="rtl"] #header .block-menu:nth-child(2) .menu {
   float: left;
 }
-#secondary-menu-links  li{
+#header .block-menu:nth-child(2) .menu li {
   margin: 0;
   padding: 0;
+    display: inline;
 }
-#secondary-menu-links  a {
+#header .block-menu:nth-child(2) .menu a {
   display: inline-block;
   padding:  0.8em;
 }
-#secondary-menu-links a:hover,
-#secondary-menu-links a:focus {
+#header .block-menu:nth-child(2) .menu a:hover,
+#header .block-menu:nth-child(2) .menu a:focus {
   text-decoration: underline;
 }
 
@@ -1875,7 +1875,7 @@ div.admin-panel .description {
   /* ------------ Header and Menus -------------------------- */
 
  .region-header {
-    margin: .5em 5px .75em;
+    margin: 0 5px 0;
   }
   #logo,
   .site-logo {
@@ -1889,13 +1889,13 @@ div.admin-panel .description {
   .site-branding-text {
     padding: 10px 10px 8px;
   }
-  #main-menu-links {
+  #header .block-menu .menu {
     margin: 0 5px;
     padding: 0;
     text-align: center;
   }
-  #main-menu-links li,
-  body:not(:target) #main-menu-links li {
+  #header .block-menu:first-child .menu li,
+  body:not(:target) #header .block-menu:first-child .menu li {
     float: left; /* LTR */
     margin-right: 5px; /* LTR */
     padding: 0;
@@ -1904,26 +1904,26 @@ div.admin-panel .description {
     height: auto;
     overflow: visible;
   }
-  [dir="rtl"] #main-menu-links li {
+  [dir="rtl"] #header .block-menu:first-child .menu li {
     float: right;
     margin-left: 5px;
     margin-right: 0;
   }
-  #main-menu-links li:nth-child(3n) {
+  #header .block-menu:first-child .menu li:nth-child(3n) {
     margin-right: -5px; /* LTR */
   }
-  [dir="rtl"] #main-menu-links li:nth-child(3n) {
+  [dir="rtl"] #header .block-menu:first-child .menu li:nth-child(3n) {
     margin-left: -5px;
     margin-right: 0;
   }
-  #main-menu-links a {
+  #header .block-menu:first-child .menu a {
     float: none;
     display: block;
     border-radius: 8px;
     margin-bottom: 5px;
     padding: 0.9em 5px;
   }
-  body:not(:target) .main-menu-reveal {
+  body:not(:target) #header .block-menu:first-child .menu-toggle {
     display: none;
   }
 }
@@ -1931,7 +1931,7 @@ div.admin-panel .description {
 @media all and (min-width: 901px) {
 
   .region-header {
-    margin: 1em 5px 1.5em;
+    margin: 0 5px 0;
   }
   #logo,
   .site-logo {
@@ -1954,13 +1954,13 @@ div.admin-panel .description {
   .site-name {
     font-size: 1.821em;
   }
-  #main-menu-links {
+  #header .block-menu:first-child .menu {
     font-size: 0.929em;
     margin: 0;
     padding: 0 15px;
   }
-  #main-menu-links li,
-  body:not(:target) #main-menu-links li {
+  #header .block-menu:first-child .menu li,
+  body:not(:target) #header .block-menu:first-child .menu li {
     float: left; /* LTR */
     list-style: none;
     padding: 0 1px;
@@ -1969,26 +1969,26 @@ div.admin-panel .description {
     height: auto;
     overflow: visible;
   }
-  [dir="rtl"] #main-menu-links li {
+  [dir="rtl"] #header .block-menu:first-child .menu li {
     float: right;
   }
-  #main-menu-links a {
+  #header .block-menu:first-child .menu a {
     float: left; /* LTR */
     padding: 0.7em 0.8em;
     margin-bottom: 0;
     border-bottom-left-radius: 0;
     border-bottom-right-radius: 0;
   }
-  [dir="rtl"] #main-menu-links a {
+  [dir="rtl"] #header .block-menu:first-child .menu a {
     float: right;
     padding: 0.7em 0.8em;
   }
-  .featured #main-menu-links li a:active,
-  .featured #main-menu-links li a.active {
+  .featured #header .block-menu:first-child .menu li a:active,
+  .featured #header .block-menu:first-child .menu li a.active {
     background: #f0f0f0;
     background: rgba(240, 240, 240, 1.0);
   }
-  body:not(:target) .main-menu-reveal {
+  body:not(:target) #header .block-menu:first-child .menu-toggle {
     display: none;
   }
 }
diff --git a/core/themes/bartik/templates/block--system-menu-block.html.twig b/core/themes/bartik/templates/block--system-menu-block.html.twig
new file mode 100644
index 0000000..1e81581
--- /dev/null
+++ b/core/themes/bartik/templates/block--system-menu-block.html.twig
@@ -0,0 +1,22 @@
+{% extends "@system/block--system-menu-block.html.twig" %}
+
+{#
+/**
+ * @file
+ * Bartik's theme implementation for a menu block.
+ *
+ * @ingroup themeable
+ */
+#}
+{% set show_anchor = "show-" ~ attributes.id|clean_id %}
+{% set hide_anchor = "hide-" ~ attributes.id|clean_id %}
+{% block content %}
+  {# When rendering a menu without label, render a menu toggle. #}
+  {% if not label_display %}
+    <div class="menu-toggle-target menu-toggle-target-show" id="{{ show_anchor }}"></div>
+    <div class="menu-toggle-target" id="{{ hide_anchor }}"></div>
+    <a class="menu-toggle" href="#{{ show_anchor }}">{{ 'Menu'|t }}</a>
+    <a class="menu-toggle menu-toggle--hide" href="#{{ hide_anchor }}">{{ 'Menu'|t }}</a>
+  {% endif %}
+  {{ content }}
+{% endblock %}
diff --git a/core/themes/bartik/templates/page.html.twig b/core/themes/bartik/templates/page.html.twig
index 2456642..b6fb10f 100644
--- a/core/themes/bartik/templates/page.html.twig
+++ b/core/themes/bartik/templates/page.html.twig
@@ -33,9 +33,6 @@
  *   added to make the site slogan visually hidden, but still accessible.
  *
  * Navigation:
- * - main_menu: The Main menu links for the site, if they have been configured.
- * - secondary_menu: The Secondary menu links for the site, if they have been
- *   configured.
  * - breadcrumb: The breadcrumb trail for the current page.
  *
  * Page content (in order of occurrence in the default page.html.twig):
@@ -79,13 +76,7 @@
 #}
 <div id="page-wrapper"><div id="page">
 
-  <header id="header" class="{{ secondary_menu ? 'with-secondary-menu' : 'without-secondary-menu' }}" role="banner" aria-label="{{ 'Site header'|t}}"><div class="section clearfix">
-   {% if secondary_menu %}
-      <nav id="secondary-menu" class="navigation" role="navigation"  aria-labelledby="links__system_secondary_menu">
-        {{ secondary_menu }}
-      </nav> <!-- /#secondary-menu -->
-    {% endif %}
-
+  <header id="header" role="banner" aria-label="{{ 'Site header'|t}}"><div class="section clearfix">
     {% if logo %}
       <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home" id="logo">
         <img src="{{ logo }}" alt="{{ 'Home'|t }}" />
@@ -119,15 +110,6 @@
 
     {{ page.header }}
 
-    {% if main_menu %}
-      <nav id ="main-menu" class="navigation" role="navigation" aria-labelledby="links__system_main_menu">
-        <div id="nav"></div>
-        <div id="no-nav"></div>
-        <a class="main-menu-reveal" href="#nav">{{ 'Menu'|t }}</a>
-        <a class="main-menu-reveal main-menu-reveal--hide" href="#no-nav">{{ 'Menu'|t }}</a>
-        {{ main_menu }}
-      </nav> <!-- /#main-menu -->
-    {% endif %}
   </div></header> <!-- /.section, /#header-->
 
   {% if messages %}
diff --git a/core/themes/seven/templates/page.html.twig b/core/themes/seven/templates/page.html.twig
index 59c316f..1a13268 100644
--- a/core/themes/seven/templates/page.html.twig
+++ b/core/themes/seven/templates/page.html.twig
@@ -27,9 +27,6 @@
  *   slogan has been disabled in theme settings.
  *
  * Navigation:
- * - main_menu: The Main menu links for the site, if they have been configured.
- * - secondary_menu: The Secondary menu links for the site, if they have been
- *   configured.
  * - breadcrumb: The breadcrumb trail for the current page.
  *
  * Page content (in order of occurrence in the default page.html.twig):