diff --git a/core/includes/entity.api.php b/core/includes/entity.api.php
index a56c1ef..591a2b0 100644
--- a/core/includes/entity.api.php
+++ b/core/includes/entity.api.php
@@ -510,6 +510,27 @@ function hook_entity_display_alter(\Drupal\entity\Plugin\Core\Entity\EntityDispl
 }
 
 /**
+ * Alters the settings used for displaying an entity form.
+ *
+ * @param \Drupal\entity\Plugin\Core\Entity\EntityFormDisplay $form_display
+ *   The entity_form_display object that will be used to display the entity form
+ *   components.
+ * @param array $context
+ *   An associative array containing:
+ *   - entity_type: The entity type, e.g., 'node' or 'user'.
+ *   - bundle: The bundle, e.g., 'page' or 'article'.
+ *   - form_mode: The form mode, e.g. 'default', 'profile', 'register'...
+ */
+function hook_entity_form_display_alter(\Drupal\entity\Plugin\Core\Entity\EntityFormDisplay $form_display, array $context) {
+  // Hide the 'user_picture' field from the register form.
+  if ($context['entity_type'] == 'user' && $context['form_mode'] == 'register') {
+    $form_display->setComponent('user_picture', array(
+      'type' => 'hidden',
+    ));
+  }
+}
+
+/**
  * Define custom entity properties.
  *
  * @param string $entity_type
diff --git a/core/includes/entity.inc b/core/includes/entity.inc
index edee557..c0e97d2 100644
--- a/core/includes/entity.inc
+++ b/core/includes/entity.inc
@@ -717,7 +717,7 @@ function entity_get_display($entity_type, $bundle, $view_mode) {
  * @return \Drupal\entity\Plugin\Core\Entity\EntityDisplay
  *   The display object that should be used to render the entity.
  *
- * @see entity_get_render_display().
+ * @see entity_get_display().
  */
 function entity_get_render_display(EntityInterface $entity, $view_mode) {
   $entity_type = $entity->entityType();
@@ -796,6 +796,44 @@ function entity_get_form_display($entity_type, $bundle, $form_mode = 'default')
 }
 
 /**
+ * Returns the entity_form_display object used to render an entity form.
+ *
+ * Depending on the configuration of the form mode for the bundle, this can be
+ * either the display object associated to the form mode, or the 'default'
+ * display.
+ *
+ * This function should only be used internally when rendering an entity form.
+ * When assigning suggested form display options for a component in a given form
+ * mode, entity_get_form_display() should be used instead, in order to avoid
+ * inadvertently modifying the output of other form modes that might happen to
+ * use the 'default' form display too. Those options will then be effectively
+ * applied only if the form mode is configured to use them.
+ *
+ * @param \Drupal\Core\Entity\EntityInterface $entity
+ *   The entity for which the form is being rendered.
+ * @param string $form_mode
+ *  The form mode being rendered.
+ *
+ * @return \Drupal\entity\Plugin\Core\Entity\EntityFormDisplay
+ *   The form display object that should be used to render the entity form.
+ *
+ * @see entity_get_form_display().
+ */
+function entity_get_render_form_display(EntityInterface $entity, $form_mode) {
+  $entity_type = $entity->entityType();
+  $bundle = $entity->bundle();
+
+  // @todo Form modes don't have custom settings yet, so always use the default
+  // form mode for now.
+  $render_form_mode = 'default';
+
+  $form_display = entity_get_form_display($entity_type, $bundle, $render_form_mode);
+  $form_display->originalMode = $form_mode;
+
+  return $form_display;
+}
+
+/**
  * Generic access callback for entity pages.
  *
  * @param \Drupal\Core\Entity\EntityInterface $entity
diff --git a/core/lib/Drupal/Core/Entity/EntityFormController.php b/core/lib/Drupal/Core/Entity/EntityFormController.php
index 6d2c9fb..796c1f2 100644
--- a/core/lib/Drupal/Core/Entity/EntityFormController.php
+++ b/core/lib/Drupal/Core/Entity/EntityFormController.php
@@ -78,12 +78,36 @@ public function form(array $form, array &$form_state, EntityInterface $entity) {
     // entity properties.
     $info = $entity->entityInfo();
     if (!empty($info['fieldable'])) {
+      // Get the entity_form_display object for this form mode (operation).
+      $form_display = entity_get_render_form_display($entity, $this->operation);
+
+      // Let modules alter the form display.
+      $form_display_context = array(
+        'entity_type' => $entity->entityType(),
+        'bundle' => $entity->bundle(),
+        'form_mode' => $this->operation,
+      );
+      drupal_alter('entity_form_display', $form_display, $form_display_context);
+
+      // Persist the altered form display in $form_state so we can use it during
+      // validation and submit.
+      $form_state['form_display'] = $form_display;
+
       field_attach_form($entity, $form, $form_state, $this->getFormLangcode($form_state));
+
+      // Assign the weights configured in the form display.
+      foreach ($form_display->getComponents() as $name => $options) {
+        if (isset($form[$name])) {
+          $form[$name]['#weight'] = $options['weight'];
+        }
+      }
     }
+
     if (!isset($form['langcode'])) {
       // If the form did not specify otherwise, default to keeping the existing
       // language of the entity or defaulting to the site default language for
       // new entities.
+      $entity = $entity->getBCEntity();
       $form['langcode'] = array(
         '#type' => 'value',
         '#value' => !$entity->isNew() ? $entity->langcode : language_default()->langcode,
diff --git a/core/lib/Drupal/Core/Entity/EntityFormControllerNG.php b/core/lib/Drupal/Core/Entity/EntityFormControllerNG.php
index ef9bc89..6b106c6 100644
--- a/core/lib/Drupal/Core/Entity/EntityFormControllerNG.php
+++ b/core/lib/Drupal/Core/Entity/EntityFormControllerNG.php
@@ -23,12 +23,12 @@ class EntityFormControllerNG extends EntityFormController {
    * Overrides EntityFormController::form().
    */
   public function form(array $form, array &$form_state, EntityInterface $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->getBCEntity(), $form, $form_state, $this->getFormLangcode($form_state));
-    }
+    parent::form($form, $form_state, $entity);
+
+    // The only difference between this method and its parent seems to be this
+    // 'langcode' form element, so unset it.
+    unset($form['langcode']);
+
     return $form;
   }
 
diff --git a/core/modules/datetime/lib/Drupal/datetime/Plugin/field/widget/DatetimeDatelistWidget.php b/core/modules/datetime/lib/Drupal/datetime/Plugin/field/widget/DatetimeDatelistWidget.php
index 366a4c4..1c5cac3 100644
--- a/core/modules/datetime/lib/Drupal/datetime/Plugin/field/widget/DatetimeDatelistWidget.php
+++ b/core/modules/datetime/lib/Drupal/datetime/Plugin/field/widget/DatetimeDatelistWidget.php
@@ -46,13 +46,11 @@ class DateTimeDatelistWidget extends WidgetBase {
    *   The field instance to which the widget is associated.
    * @param array $settings
    *   The widget settings.
-   * @param int $weight
-   *   The widget weight.
    */
-  public function __construct($plugin_id, array $plugin_definition, FieldInstance $instance, array $settings, $weight) {
+  public function __construct($plugin_id, array $plugin_definition, FieldInstance $instance, array $settings) {
     // Identify the function used to set the default value.
     $instance['default_value_function'] = $this->defaultValueFunction();
-    parent::__construct($plugin_id, $plugin_definition, $instance, $settings, $weight);
+    parent::__construct($plugin_id, $plugin_definition, $instance, $settings);
   }
 
   /**
diff --git a/core/modules/datetime/lib/Drupal/datetime/Plugin/field/widget/DatetimeDefaultWidget.php b/core/modules/datetime/lib/Drupal/datetime/Plugin/field/widget/DatetimeDefaultWidget.php
index d51bac4..683ae6e 100644
--- a/core/modules/datetime/lib/Drupal/datetime/Plugin/field/widget/DatetimeDefaultWidget.php
+++ b/core/modules/datetime/lib/Drupal/datetime/Plugin/field/widget/DatetimeDefaultWidget.php
@@ -40,13 +40,11 @@ class DateTimeDefaultWidget extends WidgetBase {
    *   The field instance to which the widget is associated.
    * @param array $settings
    *   The widget settings.
-   * @param int $weight
-   *   The widget weight.
    */
-  public function __construct($plugin_id, array $plugin_definition, FieldInstance $instance, array $settings, $weight) {
+  public function __construct($plugin_id, array $plugin_definition, FieldInstance $instance, array $settings) {
     // Identify the function used to set the default value.
     $instance['default_value_function'] = $this->defaultValueFunction();
-    parent::__construct($plugin_id, $plugin_definition, $instance, $settings, $weight);
+    parent::__construct($plugin_id, $plugin_definition, $instance, $settings);
   }
 
   /**
diff --git a/core/modules/field/field.api.php b/core/modules/field/field.api.php
index 9be355e..eaa5019 100644
--- a/core/modules/field/field.api.php
+++ b/core/modules/field/field.api.php
@@ -21,7 +21,6 @@
  * in a #pre_render callback added by field_attach_form() and
  * field_attach_view().
  *
- * @see _field_extra_fields_pre_render()
  * @see hook_field_extra_fields_alter()
  *
  * @return array
diff --git a/core/modules/field/field.attach.inc b/core/modules/field/field.attach.inc
index 0a373d1..0fe5114 100644
--- a/core/modules/field/field.attach.inc
+++ b/core/modules/field/field.attach.inc
@@ -705,15 +705,15 @@ function _field_invoke_get_instances($entity_type, $bundle, $options) {
  *
  * Used to invoke methods on an instance's widget.
  *
- * @param \Drupal\entity\Plugin\Core\Entity\EntityFormDisplay $entity_form_display
+ * @param \Drupal\entity\Plugin\Core\Entity\EntityFormDisplay $form_display
  *   An EntityFormDisplay object.
  *
  * @return callable $target_function
  *   A 'target function' for field_invoke_method().
  */
-function _field_invoke_widget_target($entity_form_display) {
-  return function ($instance) use ($entity_form_display) {
-    return $entity_form_display->getWidget($instance['field_name']);
+function _field_invoke_widget_target($form_display) {
+  return function ($instance) use ($form_display) {
+    return $form_display->getWidget($instance['field_name']);
   };
 }
 
@@ -825,18 +825,19 @@ function _field_invoke_widget_target($entity_form_display) {
  * @see field_form_set_state()
  */
 function field_attach_form(EntityInterface $entity, &$form, &$form_state, $langcode = NULL, array $options = array()) {
+  // Enable BC if necessary.
+  $entity = $entity->getBCEntity();
+
   // Set #parents to 'top-level' by default.
   $form += array('#parents' => array());
 
-  // Get the entity_form_display object for this bundle.
-  $entity_form_display = entity_get_form_display($entity->entityType(), $entity->bundle());
+  // Get the entity_form_display object for this form.
+  $form_display = $form_state['form_display'];
 
   // If no language is provided use the default site language.
   $options['langcode'] = field_valid_language($langcode);
-  $form += (array) field_invoke_method('form', _field_invoke_widget_target($entity_form_display), $entity, $form, $form_state, $options);
+  $form += (array) field_invoke_method('form', _field_invoke_widget_target($form_display), $entity, $form, $form_state, $options);
 
-  // Add custom weight handling.
-  $form['#pre_render'][] = '_field_extra_fields_pre_render';
   $form['#entity_type'] = $entity->entityType();
   $form['#bundle'] = $entity->bundle();
 
@@ -1098,8 +1099,8 @@ function field_attach_form_validate(EntityInterface $entity, $form, &$form_state
         field_form_set_state($form['#parents'], $field_name, $langcode, $form_state, $field_state);
       }
     }
-    $entity_form_display = entity_get_form_display($entity->entityType(), $entity->bundle());
-    field_invoke_method('flagErrors', _field_invoke_widget_target($entity_form_display), $entity, $form, $form_state, $options);
+    $form_display = $form_state['form_display'];
+    field_invoke_method('flagErrors', _field_invoke_widget_target($form_display), $entity, $form, $form_state, $options);
   }
 }
 
@@ -1123,8 +1124,8 @@ function field_attach_form_validate(EntityInterface $entity, $form, &$form_state
  */
 function field_attach_extract_form_values(EntityInterface $entity, $form, &$form_state, array $options = array()) {
   // Extract field values from submitted values.
-  $entity_form_display = entity_get_form_display($entity->entityType(), $entity->bundle());
-  field_invoke_method('extractFormValues', _field_invoke_widget_target($entity_form_display), $entity, $form, $form_state, $options);
+  $form_display = $form_state['form_display'];
+  field_invoke_method('extractFormValues', _field_invoke_widget_target($form_display), $entity, $form, $form_state, $options);
 
   // Let other modules act on submitting the entity.
   // Avoid module_invoke_all() to let $form_state be taken by reference.
diff --git a/core/modules/field/field.module b/core/modules/field/field.module
index 5f774ad..42146a8 100644
--- a/core/modules/field/field.module
+++ b/core/modules/field/field.module
@@ -645,23 +645,6 @@ function field_view_mode_settings($entity_type, $bundle) {
 }
 
 /**
- * Pre-render callback: Adjusts weights and visibility of non-field elements.
- */
-function _field_extra_fields_pre_render($elements) {
-  $entity_type = $elements['#entity_type'];
-  $bundle = $elements['#bundle'];
-
-  $extra_fields = field_info_extra_fields($entity_type, $bundle, 'form');
-  foreach ($extra_fields as $name => $settings) {
-    if (isset($elements[$name])) {
-      $elements[$name]['#weight'] = $settings['weight'];
-    }
-  }
-
-  return $elements;
-}
-
-/**
  * Clears the field info and field data caches.
  */
 function field_cache_clear() {
diff --git a/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetBase.php b/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetBase.php
index fccbd1a..ab0d945 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetBase.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetBase.php
@@ -39,13 +39,6 @@
   protected $settings;
 
   /**
-   * The widget weight.
-   *
-   * @var int
-   */
-  protected $weight;
-
-  /**
    * Constructs a WidgetBase object.
    *
    * @param array $plugin_id
@@ -56,16 +49,13 @@
    *   The field instance to which the widget is associated.
    * @param array $settings
    *   The widget settings.
-   * @param int $weight
-   *   The widget weight.
    */
-  public function __construct($plugin_id, array $plugin_definition, FieldInstance $instance, array $settings, $weight) {
+  public function __construct($plugin_id, array $plugin_definition, FieldInstance $instance, array $settings) {
     parent::__construct(array(), $plugin_id, $plugin_definition);
 
     $this->instance = $instance;
     $this->field = field_info_field($instance['field_name']);
     $this->settings = $settings;
-    $this->weight = $weight;
   }
 
   /**
@@ -140,7 +130,6 @@ public function form(EntityInterface $entity, $langcode, array $items, array &$f
           'field-widget-' . drupal_html_class($this->getPluginId()),
         ),
       ),
-      '#weight' => $this->weight,
     );
 
     // Populate the 'array_parents' information in $form_state['field'] after
diff --git a/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetFactory.php b/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetFactory.php
index 392ef5e..9b14e85 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetFactory.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Type/Widget/WidgetFactory.php
@@ -20,6 +20,6 @@ class WidgetFactory extends DefaultFactory {
   public function createInstance($plugin_id, array $configuration) {
     $plugin_definition = $this->discovery->getDefinition($plugin_id);
     $plugin_class = static::getPluginClass($plugin_id, $plugin_definition);
-    return new $plugin_class($plugin_id, $plugin_definition, $configuration['instance'], $configuration['settings'], $configuration['weight']);
+    return new $plugin_class($plugin_id, $plugin_definition, $configuration['instance'], $configuration['settings']);
   }
 }
diff --git a/core/modules/options/lib/Drupal/options/Plugin/field/widget/OptionsWidgetBase.php b/core/modules/options/lib/Drupal/options/Plugin/field/widget/OptionsWidgetBase.php
index 40f24df..94ae0cb 100644
--- a/core/modules/options/lib/Drupal/options/Plugin/field/widget/OptionsWidgetBase.php
+++ b/core/modules/options/lib/Drupal/options/Plugin/field/widget/OptionsWidgetBase.php
@@ -36,8 +36,8 @@
   /**
    * {@inheritdoc}
    */
-  public function __construct($plugin_id, array $plugin_definition, FieldInstance $instance, array $settings, $weight) {
-    parent::__construct($plugin_id, $plugin_definition, $instance, $settings, $weight);
+  public function __construct($plugin_id, array $plugin_definition, FieldInstance $instance, array $settings) {
+    parent::__construct($plugin_id, $plugin_definition, $instance, $settings);
 
     // Reset internal pointer since we're dealing with objects now.
     reset($this->field['columns']);
diff --git a/core/modules/telephone/lib/Drupal/telephone/Tests/TelephoneFieldTest.php b/core/modules/telephone/lib/Drupal/telephone/Tests/TelephoneFieldTest.php
index b705db4..0d5aa47 100644
--- a/core/modules/telephone/lib/Drupal/telephone/Tests/TelephoneFieldTest.php
+++ b/core/modules/telephone/lib/Drupal/telephone/Tests/TelephoneFieldTest.php
@@ -64,18 +64,15 @@ function testTelephoneField() {
       'label' => 'Telephone Number',
       'entity_type' => 'node',
       'bundle' => 'article',
-      'widget' => array(
-        'type' => 'telephone_default',
-        'settings' => array(
-          'placeholder' => '123-456-7890',
-        ),
-      ),
     );
     field_create_instance($instance);
 
     entity_get_form_display('node', 'article', 'default')
       ->setComponent('field_telephone', array(
         'type' => 'telephone_default',
+        'settings' => array(
+          'placeholder' => '123-456-7890',
+        ),
       ))
       ->save();