diff --git a/core/lib/Drupal/Core/Entity/ContentEntityFormController.php b/core/lib/Drupal/Core/Entity/ContentEntityFormController.php
index 7f613bc..5062444 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityFormController.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityFormController.php
@@ -48,12 +48,7 @@ public static function create(ContainerInterface $container) {
    */
   public function form(array $form, array &$form_state) {
     $entity = $this->entity;
-    // @todo Exploit the Field API to generate the default widgets for the
-    // entity fields.
-    $info = $entity->entityInfo();
-    if (!empty($info['fieldable'])) {
-      field_attach_form($entity, $form, $form_state, $this->getFormLangcode($form_state));
-    }
+    $this->attachWidgets($entity, $form, $form_state);
 
     // Add a process callback so we can assign weights and hide extra fields.
     $form['#process'][] = array($this, 'processForm');
@@ -61,32 +56,49 @@ public function form(array $form, array &$form_state) {
     return $form;
   }
 
+  public function attachWidgets(EntityInterface $entity, &$form, &$form_state) {
+    // Set #parents to 'top-level' by default.
+    $form += array('#parents' => array());
+
+    // Let each widget generate the form elements.
+    $form_display = $form_state['form_display'];
+    foreach ($entity as $name => $items) {
+      $items->filterEmptyValues();
+      if ($widget = $form_display->getRenderer($name)) {
+        $form += $widget->form($items, $form, $form_state);
+      }
+    }
+
+    $form['#entity_type'] = $entity->entityType();
+    $form['#bundle'] = $entity->bundle();
+  }
+
   /**
    * {@inheritdoc}
    */
   public function validate(array $form, array &$form_state) {
     $this->updateFormLangcode($form_state);
     $entity = $this->buildEntity($form, $form_state);
-    $entity_type = $entity->entityType();
-    $entity_langcode = $entity->language()->id;
 
     $violations = array();
-    foreach ($entity as $field_name => $field) {
-      $field_violations = $field->validate();
+    foreach ($entity as $name => $items) {
+      $field_violations = $items->validate();
       if (count($field_violations)) {
-        $violations[$field_name] = $field_violations;
+        $violations[$name] = $field_violations;
       }
     }
 
     // Map errors back to form elements.
+    $form_display = $form_state['form_display'];
     if ($violations) {
       foreach ($violations as $field_name => $field_violations) {
         $field_state = field_form_get_state($form['#parents'], $field_name, $form_state);
         $field_state['constraint_violations'] = $field_violations;
         field_form_set_state($form['#parents'], $field_name, $form_state, $field_state);
+        if ($widget = $form_display->getRenderer($name)) {
+          $widget->flagErrors($items, $form, $form_state);
+        }
       }
-
-      field_invoke_method('flagErrors', _field_invoke_widget_target($form_state['form_display']), $entity, $form, $form_state);
     }
 
     // @todo Remove this.
@@ -154,10 +166,14 @@ public function buildEntity(array $form, array &$form_state) {
       }
     }
 
-    // Invoke field API for copying field values.
-    if ($info['fieldable']) {
-      field_attach_extract_form_values($entity, $form, $form_state, array('langcode' => $this->getFormLangcode($form_state)));
+    // Extract widget values.
+    $form_display = $form_state['form_display'];
+    foreach ($entity as $name => $items) {
+      if ($widget = $form_display->getRenderer($name)) {
+        $widget->extractFormValues($items, $form, $form_state);
+      }
     }
+
     return $entity;
   }
 
diff --git a/core/modules/node/node.api.php b/core/modules/node/node.api.php
index d53673c..ccb0fdd 100644
--- a/core/modules/node/node.api.php
+++ b/core/modules/node/node.api.php
@@ -753,9 +753,7 @@ function hook_node_validate(\Drupal\Core\Entity\EntityInterface $node, $form, &$
  * "Preview" button, after form values have been copied to the form state's node
  * object, but before the node is saved or previewed. It is a chance for modules
  * to adjust the node's properties from what they are simply after a copy from
- * $form_state['values']. This hook is intended for adjusting non-field-related
- * properties. See hook_field_attach_extract_form_values() for customizing
- * field-related properties.
+ * $form_state['values'].
  *
  * @param \Drupal\Core\Entity\EntityInterface $node
  *   The node entity being updated in response to a form submission.
diff --git a/core/modules/user/lib/Drupal/user/RegisterFormController.php b/core/modules/user/lib/Drupal/user/RegisterFormController.php
index 38612a2..7acaa4a 100644
--- a/core/modules/user/lib/Drupal/user/RegisterFormController.php
+++ b/core/modules/user/lib/Drupal/user/RegisterFormController.php
@@ -42,9 +42,6 @@ public function form(array $form, array &$form_state) {
     // Start with the default user account fields.
     $form = parent::form($form, $form_state, $account);
 
-    // Attach field widgets.
-    field_attach_form($account, $form, $form_state);
-
     if ($admin) {
       // Redirect back to page which initiated the create request; usually
       // admin/people/create.