diff --git a/core/includes/form.inc b/core/includes/form.inc
index e2e4dd2..e3ae228 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -530,11 +530,10 @@ function drupal_rebuild_form($form_id, &$form_state, $old_form = NULL) {
  * Fetches a form from the cache.
  */
 function form_get_cache($form_build_id, &$form_state) {
-  if ($form = drupal_container()->get('keyvalue.expirable')->get('form')->get($form_build_id)) {
+  if ($form = Drupal::service('keyvalue.expirable')->get('form')->get($form_build_id)) {
     global $user;
     if ((isset($form['#cache_token']) && drupal_valid_token($form['#cache_token'])) || (!isset($form['#cache_token']) && !$user->uid)) {
-      $stored_form_state = drupal_container()->get('keyvalue.expirable')->get('form_state')->get($form_build_id);
-      if ($stored_form_state) {
+      if ($stored_form_state = Drupal::service('keyvalue.expirable')->get('form_state')->get($form_build_id)) {
         // Re-populate $form_state for subsequent rebuilds.
         $form_state = $stored_form_state + $form_state;
 
@@ -568,12 +567,12 @@ function form_set_cache($form_build_id, $form, $form_state) {
     if ($GLOBALS['user']->uid) {
       $form['#cache_token'] = drupal_get_token();
     }
-    drupal_container()->get('keyvalue.expirable')->get('form')->setWithExpire($form_build_id, $form, $expire);
+    Drupal::service('keyvalue.expirable')->get('form')->setWithExpire($form_build_id, $form, $expire);
   }
 
   // Cache form state.
   if ($data = array_diff_key($form_state, array_flip(form_state_keys_no_cache()))) {
-    drupal_container()->get('keyvalue.expirable')->get('form_state')->setWithExpire($form_build_id, $data, $expire);
+    Drupal::service('keyvalue.expirable')->get('form_state')->setWithExpire($form_build_id, $data, $expire);
   }
 }
 
@@ -915,15 +914,6 @@ function drupal_process_form($form_id, &$form, &$form_state) {
       // Execute form submit handlers.
       form_execute_handlers('submit', $form, $form_state);
 
-      // We'll clear out the cached copies of the form and its stored data
-      // here, as we've finished with them. The in-memory copies are still
-      // here, though.
-      $config = config('system.performance');
-      if (!$config->get('cache.page.use_internal') && !empty($form_state['values']['form_build_id'])) {
-        drupal_container()->get('keyvalue.expirable')->get('form')->delete($form_state['values']['form_build_id']);
-        drupal_container()->get('keyvalue.expirable')->get('form_state')->delete($form_state['values']['form_build_id']);
-      }
-
       // If batches were set in the submit handlers, we process them now,
       // possibly ending execution. We make sure we do not react to the batch
       // that is already being processed (if a batch operation performs a