diff -u b/core/includes/menu.inc b/core/includes/menu.inc
--- b/core/includes/menu.inc
+++ b/core/includes/menu.inc
@@ -777,13 +777,15 @@
   $router_item['tab_parent_href'] = implode('/', $tab_parent_map);
   $router_item['options'] = array();
   if (!empty($router_item['route_name'])) {
-    // Route-provided menu items do not have menu loaders, so replace the map
-    // with the link map.
-    $map = $link_map;
-
     $route_provider = Drupal::getContainer()->get('router.route_provider');
     $route = $route_provider->getRouteByName($router_item['route_name']);
-    $router_item['access'] = menu_item_route_access($route, $router_item['href'], $map);
+    // Create a mock request for the path.
+    $request = Request::create('/' . $router_item['href']);
+    $request->attributes->set('system_path', $router_item['href']);
+    $router_item['access'] = menu_item_route_access($route, $request);
+    // Route-provided menu items do not have menu loaders, so replace the map
+    // with the link map and populate any placeholders.
+    $map = menu_item_populate_map($route, $request, $link_map);
   }
   else {
     // @todo: Remove once all routes are converted.
@@ -921,7 +923,11 @@
     // menu_tree_check_access() may set this ahead of time for links to nodes.
     if (!isset($item['access'])) {
       if ($route = $item->getRoute()) {
-        $item['access'] = menu_item_route_access($route, $item['href'], $map);
+        // Create a mock request for the path.
+        $request = Request::create('/' . $item['href']);
+        $request->attributes->set('system_path', $item['href']);
+        $item['access'] = menu_item_route_access($route, $request);
+        $map = menu_item_populate_map($route, $request, $map);
       }
       elseif (!empty($item['load_functions']) && !_menu_load_objects($item, $map)) {
         // An error occurred loading an object.
@@ -951,31 +957,43 @@
 }
 
 /**
- * Checks access to a menu item by mocking a request for a path.
+ * Checks access to a menu item.
  *
  * @param \Symfony\Component\Routing\Route $route
  *   Router for the given menu item.
- * @param string $href
- *   Menu path as returned by $item['href'] of menu_get_item().
- * @param array $map
- *   An array of path arguments, for example, array('node', '5').
+ * @param \Symfony\Component\HttpFoundation\Request $request
+ *   The mock a request for a path.
  *
  * @return bool
  *   TRUE if the user has access or FALSE if the user should be presented
  *   with access denied.
  */
-function menu_item_route_access(Route $route, $href, &$map) {
-  $request = Request::create('/' . $href);
-  $request->attributes->set('system_path', $href);
+function menu_item_route_access(Route $route, Request $request) {
   // Attempt to match this path to provide a fully built request to the
   // access checker.
   try {
     $request->attributes->add(Drupal::service('router.dynamic')->matchRequest($request));
+    return Drupal::service('access_manager')->check($route, $request);
   }
   catch (NotFoundHttpException $e) {
     return FALSE;
   }
+}
 
+/**
+ * Populate the map with any matching values from the request.
+ *
+ * @param \Symfony\Component\Routing\Route $route
+ *   Router for the given menu item.
+ * @param \Symfony\Component\HttpFoundation\Request $request
+ *   The mock a request for a path.
+ * @param array $map
+ *   The map.
+ *
+ * return array
+ *   The populated map.
+ */
+function menu_item_populate_map(Route $route, Request $request, array $map) {
   // Populate the map with any matching values from the request.
   $path_bits = explode('/', trim($route->getPath(), '/'));
   foreach ($map as $index => $map_item) {
@@ -990,8 +1008,7 @@
       }
     }
   }
-
-  return Drupal::service('access_manager')->check($route, $request);
+  return $map;
 }
 
 /**