diff --git a/includes/form.inc b/includes/form.inc
index c1e55ec7250ecb910d1e0834abf815b074de3277..c2c179026f1d1a876095a2fecdc5c296fe939e2c 100644
--- a/includes/form.inc
+++ b/includes/form.inc
@@ -163,7 +163,9 @@
  *   Any additional arguments are passed on to the functions called by
  *   drupal_get_form(), including the unique form constructor function. For
  *   example, the node_edit form requires that a node object is passed in here
- *   when it is called.
+ *   when it is called. These are available to implementations of 
+ *   hook_form_alter() and hook_form_FORM_ID_alter() as the array
+ *   $form_state['build_info']['args'].
  *
  * @return
  *   The form array.
diff --git a/modules/system/system.api.php b/modules/system/system.api.php
index d26548131a6d5a2fcf0e98465bb54b9935f076e9..4959f098b62b2bf0e956b63952aefd64e466f6d6 100644
--- a/modules/system/system.api.php
+++ b/modules/system/system.api.php
@@ -1404,7 +1404,9 @@ function hook_page_alter(&$page) {
  * @param $form
  *   Nested array of form elements that comprise the form.
  * @param $form_state
- *   A keyed array containing the current state of the form.
+ *   A keyed array containing the current state of the form. The arguments
+ *   that drupal_get_form() was originally called with are available in the
+ *   array $form_state['build_info']['args'].
  * @param $form_id
  *   String representing the name of the form itself. Typically this is the
  *   name of the function that generated the form.
@@ -1432,7 +1434,9 @@ function hook_form_alter(&$form, &$form_state, $form_id) {
  * @param $form
  *   Nested array of form elements that comprise the form.
  * @param $form_state
- *   A keyed array containing the current state of the form.
+ *   A keyed array containing the current state of the form. The arguments
+ *   that drupal_get_form() was originally called with are available in the
+ *   array $form_state['build_info']['args'].
  * @param $form_id
  *   String representing the name of the form itself. Typically this is the
  *   name of the function that generated the form.