diff --git includes/menu.inc includes/menu.inc
index bae3750..11ff197 100644
--- includes/menu.inc
+++ includes/menu.inc
@@ -1057,7 +1057,19 @@ function menu_tree_page_data($menu_name, $max_depth = NULL) {
   $tree = &drupal_static(__FUNCTION__, array());
 
   // Load the menu item corresponding to the current page.
-  if ($item = menu_get_item()) {
+  $active_trail = menu_get_active_trail();
+  // Find the deepest item in the active trail that is in the menu system.
+  do {
+    $item = array_pop($active_trail);
+  } while (isset($item) && $item['type'] == 0);
+  if (!empty($item['href'])) {
+    $item = menu_get_item($item['href']);
+  }
+  // If we didn't find a menu item, load the menu item corresponding to the current page.
+  if (!$item) {
+    $item = menu_get_item();
+  }
+  if ($item) {
     if (isset($max_depth)) {
       $max_depth = min($max_depth, MENU_MAX_DEPTH);
     }
@@ -1271,6 +1283,8 @@ function _menu_build_tree($menu_name, array $parameters = array()) {
     }
     $active_link = (isset($parameters['active_trail']) ? $parameters['active_trail'] : array());
     $data['tree'] = menu_tree_data($links, $active_link, $min_depth);
+    // Allow the tree to be altered before any access checks.
+    drupal_alter('menu_tree', $data['tree'], $parameters);
     $data['node_links'] = array();
     menu_tree_collect_node_links($data['tree'], $data['node_links']);
 
@@ -2105,6 +2119,11 @@ function menu_set_active_item($path) {
 /**
  * Sets or gets the active trail (path to root menu root) of the current page.
  *
+ * If a trail is set, it must exist in the menu system since this trail is used
+ * by menu_tree_page_data() and menu_get_active_breadcrumb() when determining
+ * the menu's active trail. In order to set a trail that does not exist in the
+ * menu system, use drupal_set_breadcrumb() instead.
+ *
  * @param $new_trail
  *   Menu trail to set, or NULL to use previously-set or calculated trail. If
  *   supplying a trail, use the same format as the return value (see below).
@@ -2193,9 +2212,9 @@ function menu_set_active_trail($new_trail = NULL) {
       }
     }
     // Make sure the current page is in the trail (needed for the page title),
-    // but exclude tabs and the front page.
+    // but exclude default tabs and the front page.
     $last = count($trail) - 1;
-    if ($trail[$last]['href'] != $item['href'] && !(bool) ($item['type'] & MENU_IS_LOCAL_TASK) && !drupal_is_front_page()) {
+    if ($trail[$last]['href'] != $item['href'] && !(bool) ($item['type'] & MENU_LINKS_TO_PARENT) && !drupal_is_front_page()) {
       $trail[] = $item;
     }
   }
@@ -2222,20 +2241,18 @@ function menu_get_active_breadcrumb() {
     return $breadcrumb;
   }
 
-  $item = menu_get_item();
-  if ($item && $item['access']) {
-    $active_trail = menu_get_active_trail();
+  $active_trail = menu_get_active_trail();
 
-    foreach ($active_trail as $parent) {
-      $breadcrumb[] = l($parent['title'], $parent['href'], $parent['localized_options']);
-    }
-    $end = end($active_trail);
+  foreach ($active_trail as $parent) {
+    $breadcrumb[] = l($parent['title'], $parent['href'], $parent['localized_options']);
+  }
+  $end = end($active_trail);
 
-    // Don't show a link to the current page in the breadcrumb trail.
-    if ($item['href'] == $end['href'] || (($item['type'] & MENU_LINKS_TO_PARENT) == MENU_LINKS_TO_PARENT && $end['href'] != '<front>')) {
-      array_pop($breadcrumb);
-    }
+  // Don't show a link to the current page in the breadcrumb trail.
+  if ($end['href'] != '<front>') {
+    array_pop($breadcrumb);
   }
+
   return $breadcrumb;
 }
 
diff --git modules/system/system.api.php modules/system/system.api.php
index d8450db..57b1f75 100644
--- modules/system/system.api.php
+++ modules/system/system.api.php
@@ -1244,6 +1244,27 @@ function hook_menu_contextual_links_alter(&$links, $router_item, $root_path) {
 }
 
 /**
+ * Alter menu trees before they are rendered.
+ *
+ * This hook is invoked by menu_build_tree(). The tree is passed through
+ * menu_tree_check_access() after this hook is called, so implementations will
+ * not need to worry about node access for any altered items.
+ *
+ * @param $tree
+ *   The menu tree to be altered.
+ * @param $parameters
+ *   An associative array of build parameters passed to menu_build_tree().
+ */
+function hook_menu_tree_alter(&$tree, $parameters = array()) {
+  // Add a "primary" class to each of the first-level links.
+  foreach ($data['tree'] as $mlid => &$item) {
+    $options = unserialize($item['link']['options']);
+    $options['attributes']['class'][] = 'primary';
+    $item['link']['options'] = serialize($options);
+  }
+}
+
+/**
  * Perform alterations before a page is rendered.
  *
  * Use this hook when you want to remove or alter elements at the page