diff --git a/includes/common.inc b/includes/common.inc
index ebc8c1c07abd0de2e7b289ee6763fe4741a3d3c5..fdd5f64d61d8dffdf1e77a2f0bb86aaf6dd38835 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -2275,10 +2275,9 @@ function l($text, $path, array $options = array()) {
  * sends the content to the browser in the needed format. The default delivery
  * callback is drupal_deliver_html_page() which delivers the content as an HTML
  * page, complete with blocks in addition to the content. This default can be
- * overridden on a per menu item basis by setting 'delivery callback' in
- * hook_menu(), hook_menu_alter().
- * Additionally, modules may use hook_page_delivery_callback_alter() to specify
- * a different delivery callback to use for the page request.
+ * overridden on a per menu router item basis by setting 'delivery callback' in
+ * hook_menu() or hook_menu_alter(), and can also be overridden on a per request
+ * basis in hook_page_delivery_callback_alter().
  *
  * For example, the same page callback function can be used for an HTML
  * version of the page and an AJAX version of the page. The page callback
@@ -2300,8 +2299,7 @@ function l($text, $path, array $options = array()) {
  *   (Optional) If given, it is the name of a delivery function most likely
  *   to be appropriate for the page request as determined by the calling
  *   function (e.g., menu_execute_active_handler()). If not given, it is
- *   determined from the menu router information of the current page. In either
- *   case, modules have a final chance to alter which function is called.
+ *   determined from the menu router information of the current page.
  *
  * @see menu_execute_active_handler()
  * @see hook_menu()
@@ -2310,14 +2308,11 @@ function l($text, $path, array $options = array()) {
  */
 function drupal_deliver_page($page_callback_result, $default_delivery_callback = NULL) {
   if (!isset($default_delivery_callback) && ($router_item = menu_get_item())) {
-    drupal_alter('menu_active_handler', $router_item);
     $default_delivery_callback = $router_item['delivery_callback'];
   }
   $delivery_callback = !empty($default_delivery_callback) ? $default_delivery_callback : 'drupal_deliver_html_page';
-  // Give modules a final chance to alter the delivery callback used. This is
-  // for modules that need to decide which delivery callback to use based on
-  // information made available during page callback execution and for pages
-  // without router items.
+  // Give modules a chance to alter the delivery callback used, based on
+  // request-time context (e.g., HTTP request headers).
   drupal_alter('page_delivery_callback', $delivery_callback);
   if (function_exists($delivery_callback)) {
     $delivery_callback($page_callback_result);
diff --git a/includes/menu.inc b/includes/menu.inc
index 0c17e595322caea211c6ac7a49a915a48272a427..83cff5f4e5b7ec909f909e32707b7d2c3a02f51c 100644
--- a/includes/menu.inc
+++ b/includes/menu.inc
@@ -457,8 +457,6 @@ function menu_execute_active_handler($path = NULL, $deliver = TRUE) {
       menu_rebuild();
     }
     if ($router_item = menu_get_item($path)) {
-      // hook_menu_alter() lets modules control menu router information that
-      // doesn't depend on the details of a particular page request.
       if ($router_item['access']) {
         if ($router_item['include_file']) {
           require_once DRUPAL_ROOT . '/' . $router_item['include_file'];
diff --git a/modules/system/system.api.php b/modules/system/system.api.php
index 467d37fbef73e35148c51d7746cb5d65378c90b7..adbc224b94756daca230360e37b97d1cd80366a6 100644
--- a/modules/system/system.api.php
+++ b/modules/system/system.api.php
@@ -3524,8 +3524,7 @@ function hook_date_formats_alter(&$formats) {
  * information unrelated to the path of the page accessed. For example,
  * it can be used to set the delivery callback based on a HTTP request
  * header (as shown in the code sample). To specify a delivery callback
- * based on path information, use hook_menu(), hook_menu_alter() or
- * hook_page_delivery_callback_alter().
+ * based on path information, use hook_menu() or hook_menu_alter().
  *
  * This hook can also be used as an API function that can be used to explicitly
  * set the delivery callback from some other function. For example, for a module