diff --git a/core/includes/menu.inc b/core/includes/menu.inc
index b9c967f..7f2a5ae 100644
--- a/core/includes/menu.inc
+++ b/core/includes/menu.inc
@@ -1555,112 +1555,53 @@ function _menu_tree_data(&$links, $parents, $depth) {
 }
 
 /**
- * Implements template_preprocess_HOOK() for theme_menu_tree().
- */
-function template_preprocess_menu_tree(&$variables) {
-  $variables['tree'] = $variables['tree']['#children'];
-}
-
-/**
- * Returns HTML for a wrapper for a menu sub-tree.
+ * Prepares variables for menu tree templates.
  *
- * @param $variables
- *   An associative array containing:
- *   - tree: An HTML string containing the tree's items.
+ * Default template: menu-tree.html.twig.
  *
- * @see template_preprocess_menu_tree()
- * @ingroup themeable
- */
-function theme_menu_tree($variables) {
-  return '<ul class="menu">' . $variables['tree'] . '</ul>';
-}
-
-/**
- * Returns HTML for a menu link and submenu.
- *
- * @param $variables
+ * @param array $variables
  *   An associative array containing:
- *   - element: Structured array data for a menu link.
- *
- * @ingroup themeable
+ *   - tree: A render array for a menu tree.
  */
-function theme_menu_link(array $variables) {
-  $element = $variables['element'];
-  $sub_menu = '';
-
-  if ($element['#below']) {
-    $sub_menu = drupal_render($element['#below']);
-  }
-  $output = l($element['#title'], $element['#href'], $element['#localized_options']);
-  return '<li' . new Attribute($element['#attributes']) . '>' . $output . $sub_menu . "</li>\n";
+function template_preprocess_menu_tree(&$variables) {
+  $variables['tree'] = $variables['tree']['#children'];
 }
 
 /**
- * Preprocess variables for a menu link and submenu.
+ * Prepares variables for menu link plus submenu templates.
  *
- * @param $variables
+ * Default template: menu-link.html.twig.
+ *
+ * @param array $variables
  *   An associative array containing:
  *   - element: Structured array data for a menu link.
- *
- * @ingroup themeable
  */
 function template_preprocess_menu_link(&$variables) {
   $element = $variables['element'];
 
-  $variables['sub_menu'] = ($element['#below']) ? drupal_render($element['#below']) : '';
+  // @todo Remove below drupal_render()?
+  $variables['sub_menu'] = ($element['#below']) ? drupal_render($element['#below']) : array();
   $variables['link'] = l($element['#title'], $element['#href'], $element['#localized_options']);
   $variables['wrapper_attributes'] = new Attribute($element['#attributes']);
 }
 
 /**
- * Returns HTML for a single local task link.
+ * Prepares variables for single local task link templates.
  *
- * @param $variables
+ * Default template: menu-local-task.html.twig.
+ *
+ * @param $array variables
  *   An associative array containing:
  *   - element: A render element containing:
  *     - #link: A menu link array with 'title', 'href', and 'localized_options'
  *       keys.
  *     - #active: A boolean indicating whether the local task is active.
- *
- * @ingroup themeable
  */
-function theme_menu_local_task($variables) {
+function template_preprocess_menu_local_task(&$variables) {
   $link = $variables['element']['#link'];
   $link += array(
     'localized_options' => array(),
   );
-  $link_text = $link['title'];
-
-  if (!empty($variables['element']['#active'])) {
-    // Add text to indicate active tab for non-visual users.
-    $active = '<span class="element-invisible">' . t('(active tab)') . '</span>';
-
-    // If the link does not contain HTML already, check_plain() it now.
-    // After we set 'html'=TRUE the link will not be sanitized by l().
-    if (empty($link['localized_options']['html'])) {
-      $link['title'] = check_plain($link['title']);
-    }
-    $link['localized_options']['html'] = TRUE;
-    $link_text = t('!local-task-title!active', array('!local-task-title' => $link['title'], '!active' => $active));
-  }
-
-  return '<li' . (!empty($variables['element']['#active']) ? ' class="active"' : '') . '>' . l($link_text, $link['href'], $link['localized_options']) . '</li>';
-}
-
-/**
- * Preprocess variables for a single local task link.
- *
- * @param $variables
- *   An associative array containing:
- *   - element: A render element containing:
- *     - #link: A menu link array with 'title', 'href', and 'localized_options'
- *       keys.
- *     - #active: A boolean indicating whether the local task is active.
- *
- * @ingroup themeable
- */
-function template_preprocess_menu_local_task(&$variables) {
-  $link = $variables['element']['#link'];
 
   $variables['wrapper_attributes'] = new Attribute();
   $variables['active'] = FALSE;
@@ -1680,40 +1621,21 @@ function template_preprocess_menu_local_task(&$variables) {
 }
 
 /**
- * Returns HTML for a single local action link.
+ * Prepares variables for single local action link templates.
  *
- * @param $variables
+ * Default template: menu-local-action.html.twig.
+ *
+ * @param array $variables
  *   An associative array containing:
  *   - element: A render element containing:
  *     - #link: A menu link array with 'title', 'href', and 'localized_options'
  *       keys.
- *
- * @ingroup themeable
- */
-function theme_menu_local_action($variables) {
-  $link = $variables['element']['#link'];
-  $link += array(
-    'href' => '',
-    'localized_options' => array(),
-  );
-  $link['localized_options']['attributes']['class'][] = 'button';
-  $link['localized_options']['attributes']['class'][] = 'button-action';
-
-  $output = '<li>';
-  $output .= l($link['title'], $link['href'], $link['localized_options']);
-  $output .= "</li>";
-
-  return $output;
-}
-
-/**
- * Preprocess variables for a single local action link template.
  */
 function template_preprocess_menu_local_action(&$variables) {
   $link = $variables['element']['#link'];
   $link += array(
     'href' => '',
-    'localized_options' => array(),
+    'localized_options' => new Attribute(),
   );
   $link['localized_options']['attributes']['class'][] = 'button';
   $link['localized_options']['attributes']['class'][] = 'button-action';
diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 4c0e580..c7a805b 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -3255,18 +3255,23 @@ function drupal_common_theme() {
     // From menu.inc.
     'menu_link' => array(
       'render element' => 'element',
+      'template' => 'menu-link',
     ),
     'menu_tree' => array(
       'render element' => 'tree',
+      'template' => 'menu-tree',
     ),
     'menu_local_task' => array(
       'render element' => 'element',
+      'template' => 'menu-local-task',
     ),
     'menu_local_action' => array(
       'render element' => 'element',
+      'template' => 'menu-local-action',
     ),
     'menu_local_tasks' => array(
       'variables' => array('primary' => array(), 'secondary' => array()),
+      'template' => 'menu-local-tasks',
     ),
     // From form.inc.
     'input' => array(
diff --git a/core/themes/stark/templates/menu.inc/menu-link.html.twig b/core/modules/system/templates/menu-link.html.twig
similarity index 88%
rename from core/themes/stark/templates/menu.inc/menu-link.html.twig
rename to core/modules/system/templates/menu-link.html.twig
index 4a4dde6..9d3146a 100644
--- a/core/themes/stark/templates/menu.inc/menu-link.html.twig
+++ b/core/modules/system/templates/menu-link.html.twig
@@ -11,8 +11,8 @@
  * Note: This template renders the content for each individual menu item in
  * menu-local-tasks.html.twig.
  *
- * @see template_preprocess
- * @see template_preprocess_menu_link
+ * @see template_preprocess()
+ * @see template_preprocess_menu_link()
  *
  * @ingroup themeable
  */
diff --git a/core/themes/stark/templates/menu.inc/menu-local-action.html.twig b/core/modules/system/templates/menu-local-action.html.twig
similarity index 71%
rename from core/themes/stark/templates/menu.inc/menu-local-action.html.twig
rename to core/modules/system/templates/menu-local-action.html.twig
index 45b9358..08bd68b 100644
--- a/core/themes/stark/templates/menu.inc/menu-local-action.html.twig
+++ b/core/modules/system/templates/menu-local-action.html.twig
@@ -6,8 +6,8 @@
  * Available variables:
  * - link: A rendered link element.
  *
- * @see template_preprocess
- * @see template_preprocess_menu_local_action
+ * @see template_preprocess()
+ * @see template_preprocess_menu_local_action()
  *
  * @ingroup themeable
  */
diff --git a/core/themes/stark/templates/menu.inc/menu-local-task.html.twig b/core/modules/system/templates/menu-local-task.html.twig
similarity index 76%
rename from core/themes/stark/templates/menu.inc/menu-local-task.html.twig
rename to core/modules/system/templates/menu-local-task.html.twig
index 029fead..2d1c516 100644
--- a/core/themes/stark/templates/menu.inc/menu-local-task.html.twig
+++ b/core/modules/system/templates/menu-local-task.html.twig
@@ -4,14 +4,14 @@
  * Default theme implementation for a local task link.
  *
  * Available variables:
- * - wrapper_attributes: An array of HTML attributes for the wrapper element.
+ * - wrapper_attributes: HTML attributes for the wrapper element.
  * - link: The rendered link (<a> tag).
  *
  * Note: This template renders the content for each individual task item in
  * menu-local-tasks.html.twig.
  *
- * @see template_preprocess
- * @see template_preprocess_menu_local_task
+ * @see template_preprocess()
+ * @see template_preprocess_menu_local_task()
  *
  * @ingroup themeable
  */
@@ -24,4 +24,4 @@
     <span class="element-invisible">({{ 'active tab'|t }})</span>
   {% endif %}
 </li>
-{% endspaceless %}
\ No newline at end of file
+{% endspaceless %}
diff --git a/core/themes/stark/templates/menu.inc/menu-local-tasks.html.twig b/core/modules/system/templates/menu-local-tasks.html.twig
similarity index 86%
rename from core/themes/stark/templates/menu.inc/menu-local-tasks.html.twig
rename to core/modules/system/templates/menu-local-tasks.html.twig
index a90921d..2ca090d 100755
--- a/core/themes/stark/templates/menu.inc/menu-local-tasks.html.twig
+++ b/core/modules/system/templates/menu-local-tasks.html.twig
@@ -10,11 +10,11 @@
  * Note: Each item for both sets of tasks can be individually themed in
  * menu-local-task.html.twig.
  *
- * @see template_preprocess
- * @see template_preprocess_menu_local_tasks
+ * @see template_preprocess()
+ * @see template_preprocess_menu_local_tasks()
  *
-* @ingroup themeable
-*/
+ * @ingroup themeable
+ */
 #}
 {% if primary_tasks %}
   <h2 class="element-invisible">{{ 'Primary tabs'|t }}</h2>
diff --git a/core/themes/stark/templates/menu.inc/menu-tree.html.twig b/core/modules/system/templates/menu-tree.html.twig
similarity index 82%
rename from core/themes/stark/templates/menu.inc/menu-tree.html.twig
rename to core/modules/system/templates/menu-tree.html.twig
index 7134dec..0dc857e 100644
--- a/core/themes/stark/templates/menu.inc/menu-tree.html.twig
+++ b/core/modules/system/templates/menu-tree.html.twig
@@ -9,8 +9,8 @@
  * Note: Each item in the menu tree can be individually themed in
  * menu-link.html.twig.
  *
- * @see template_preprocess
- * @see template_preprocess_menu_tree
+ * @see template_preprocess()
+ * @see template_preprocess_menu_tree()
  *
  * @ingroup themeable
  */