diff --git a/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php b/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php
index faa6d0d..fd3535f 100644
--- a/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php
+++ b/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Core\Entity\Entity;
 
+use Drupal\Component\Utility\SortArray;
 use Drupal\Core\Entity\EntityConstraintViolationListInterface;
 use Drupal\Core\Entity\EntityDisplayPluginCollection;
 use Drupal\Core\Entity\FieldableEntityInterface;
@@ -160,8 +161,14 @@ public function buildForm(FieldableEntityInterface $entity, array &$form, FormSt
     // Set #parents to 'top-level' by default.
     $form += ['#parents' => []];
 
+    // Sort the components by their weight in order to allow a form element from
+    // a widget to depend on the processed elements of another form element from
+    // a another widget.
+    $components = $this->getComponents();
+    uasort($components, ['Drupal\Component\Utility\SortArray', 'sortByWeightElement']);
+
     // Let each widget generate the form elements.
-    foreach ($this->getComponents() as $name => $options) {
+    foreach ($components as $name => $options) {
       if ($widget = $this->getRenderer($name)) {
         $items = $entity->get($name);
         $items->filterEmptyItems();
diff --git a/core/lib/Drupal/Core/Entity/EntityAccessControlHandler.php b/core/lib/Drupal/Core/Entity/EntityAccessControlHandler.php
index ac36411..a021b05 100644
--- a/core/lib/Drupal/Core/Entity/EntityAccessControlHandler.php
+++ b/core/lib/Drupal/Core/Entity/EntityAccessControlHandler.php
@@ -316,15 +316,11 @@ public function fieldAccess($operation, FieldDefinitionInterface $field_definiti
     $default = $items ? $items->defaultAccess($operation, $account) : AccessResult::allowed();
 
     // Explicitly disallow changing the entity ID and entity UUID.
-    if ($operation === 'edit') {
-      if ($field_definition->getName() === $this->entityType->getKey('id')) {
-        return $return_as_object ? AccessResult::forbidden('The entity ID cannot be changed') : FALSE;
-      }
-      elseif ($field_definition->getName() === $this->entityType->getKey('uuid')) {
-        // UUIDs can be set when creating an entity.
-        if ($items && ($entity = $items->getEntity()) && !$entity->isNew()) {
-          return $return_as_object ? AccessResult::forbidden('The entity UUID cannot be changed')->addCacheableDependency($entity) : FALSE;
-        }
+    if ($operation === 'edit' &&
+        ($field_definition->getName() === $this->entityType->getKey('id') || $field_definition->getName() === $this->entityType->getKey('uuid'))) {
+      // IDs and UUIDs can be set when creating an entity.
+      if ($items && ($entity = $items->getEntity()) && !$entity->isNew()) {
+        return $return_as_object ? AccessResult::forbidden('The entity ' . $field_definition->getLabel() . ' cannot be changed') : FALSE;
       }
     }
 
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/StringMachineNameWidget.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/StringMachineNameWidget.php
new file mode 100644
index 0000000..44d10fa
--- /dev/null
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/StringMachineNameWidget.php
@@ -0,0 +1,105 @@
+<?php
+
+namespace Drupal\Core\Field\Plugin\Field\FieldWidget;
+
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Field\WidgetBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Plugin implementation of the 'string_machine_name' widget.
+ *
+ * @FieldWidget(
+ *   id = "string_machine_name",
+ *   label = @Translation("Machine name"),
+ *   field_types = {
+ *     "string"
+ *   }
+ * )
+ */
+class StringMachineNameWidget extends WidgetBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function defaultSettings() {
+    return [
+      'source' => '',
+      'exists' => '',
+      'label' => '',
+      'replace_pattern' => '',
+      'replace' => '',
+    ] + parent::defaultSettings();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsForm(array $form, FormStateInterface $form_state) {
+    $entity_type = $this->fieldDefinition->getTargetEntityTypeId();
+    $bundle = $this->fieldDefinition->getTargetBundle();
+    $fields = [];
+    /**@var \Drupal\Core\Field\FieldDefinitionInterface $field */
+    foreach (\Drupal::service('entity_field.manager')->getFieldDefinitions($entity_type, $bundle) as $field_name => $field) {
+      $fields[$field_name] = $field->getLabel();
+    }
+    $element['source'] = [
+      '#type' => 'select',
+      '#title' => $this->t('Source field'),
+      '#default_value' => $this->getSetting('source'),
+      '#options' => $fields,
+      '#description' => $this->t('The field that should be used as a source for the machine name element.'),
+    ];
+
+    // @todo Add the rest of the settings.
+
+    return $element;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsSummary() {
+    $summary = [];
+
+    // @todo Add summaries for some of the settings, probably not all.
+
+    return $summary;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
+    $element['value'] = $element + [
+      '#type' => 'machine_name',
+      '#default_value' => isset($items[$delta]->value) ? $items[$delta]->value : NULL,
+      '#maxlength' => $this->getFieldSetting('max_length'),
+      '#machine_name' => [
+        // @todo Generate the machine name configuration from the widget
+        //   settings. Initially, the source field might look like this, but we
+        //   need to generate it in an #after_build callback. See below.
+        //'source' => ['name', 'widget', 0, 'value'],
+      ],
+    ];
+
+    return $element;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function afterBuild(array $element, FormStateInterface $form_state) {
+    $element = parent::afterBuild($element, $form_state);
+
+    $form = $form_state->getCompleteForm();
+
+    // @todo We need to override $element['value']['#machine_name']['source']
+    // with the actual location of the source field in the form, taking into
+    // account that this could be a subform as part of a larger parent form
+    // (i.e. Inline Entity Form).
+
+    return $element;
+  }
+
+}
diff --git a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestStringId.php b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestStringId.php
index 342cbb9..abbf5c0 100644
--- a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestStringId.php
+++ b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestStringId.php
@@ -49,7 +49,12 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ->setReadOnly(TRUE)
       // In order to work around the InnoDB 191 character limit on utf8mb4
       // primary keys, we set the character set for the field to ASCII.
-      ->setSetting('is_ascii', TRUE);
+      ->setSetting('is_ascii', TRUE)
+      ->setDisplayOptions('form', [
+        'type' => 'string_machine_name',
+        'weight' => -1,
+      ])
+      ->setDisplayConfigurable('form', TRUE);
     return $fields;
   }