diff --git includes/common.inc includes/common.inc
index 0bae037..59d179a 100644
--- includes/common.inc
+++ includes/common.inc
@@ -6687,15 +6687,20 @@ function entity_form_field_validate($entity_type, $form, &$form_state) {
  * possibly other buttons, the form state's entity needs to be updated with the
  * submitted form values. Each entity form implements its own
  * $form['#builder_function'] for doing this, appropriate for the particular
- * entity and form. Many of these entity builder functions can call this helper
+ * entity and form, whereas modules may specify additional builder functions
+ * in $form['#builder'] for copying the form values of added form elements to
+ * entity properties.
+ * Many of the main entity builder functions can call this helper
  * function to re-use its logic of copying $form_state['values'][PROPERTY]
  * values to $entity->PROPERTY for all entries in $form_state['values'] that are
- * not field data, and calling field_attach_submit() to copy field data.
+ * not field data, and calling field_attach_submit() to copy field data. Also
+ * this helper invokes any additional, in $form['#builder'] specified builder
+ * functions.
  *
  * For some entity forms (e.g., forms with complex non-field data and forms that
  * simultaneously edit multiple entities), this behavior may be inappropriate,
  * so the #builder_function for such forms needs to implement the required
- * functionality instead of calling this function. 
+ * functionality instead of calling this function.
  */
 function entity_form_submit_build_entity($entity_type, $entity, $form, &$form_state) {
   $info = entity_get_info($entity_type);
@@ -6709,6 +6714,13 @@ function entity_form_submit_build_entity($entity_type, $entity, $form, &$form_st
     $entity->$key = $value;
   }
 
+  // Invoke all specified builders for copying form values to entity properties.
+  if (isset($form['#builder'])) {
+    foreach ($form['#builder'] as $function) {
+      $function($entity_type, $entity, $form, $form_state);
+    }
+  }
+
   // Copy field values to the entity.
   if ($info['fieldable']) {
     field_attach_submit($entity_type, $entity, $form, $form_state);