diff --git a/core/lib/Drupal/Core/Entity/EntityManager.php b/core/lib/Drupal/Core/Entity/EntityManager.php
index 3ab60f5..40f0efe 100644
--- a/core/lib/Drupal/Core/Entity/EntityManager.php
+++ b/core/lib/Drupal/Core/Entity/EntityManager.php
@@ -30,6 +30,7 @@
 use Drupal\Core\StringTranslation\TranslationInterface;
 use Drupal\Core\TypedData\TranslatableInterface;
 use Drupal\Core\TypedData\TypedDataManager;
+use Drupal\field\Entity\FieldConfig;
 use Symfony\Component\DependencyInjection\ContainerAwareInterface;
 use Symfony\Component\DependencyInjection\ContainerAwareTrait;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
@@ -168,6 +169,14 @@ class EntityManager extends DefaultPluginManager implements EntityManagerInterfa
   protected $fieldMapByFieldType = array();
 
   /**
+   * A list of entity reference fields targeting to a specific entity type and
+   * bundle.
+   *
+   * @var array
+   */
+  protected $fieldsReferencing = array();
+
+  /**
    * Contains cached mappings of class names to entity types.
    *
    * @var array
@@ -678,6 +687,42 @@ public function getFieldMapByFieldType($field_type) {
   }
 
   /**
+   * {@inheritdoc}
+   */
+  public function getFieldsReferencing($target_type, $target_bundle) {
+    if (!isset($this->fieldsReferencing[$target_type][$target_bundle])) {
+      $map = $this->getFieldMapByFieldType('entity_reference');
+      $ids = [];
+      foreach ($map as $type => $info) {
+        foreach ($info as $name => $data) {
+          foreach ($data['bundles'] as $bundle) {
+            $ids[] = "$type.$bundle.$name";
+          }
+        }
+      }
+
+      $this->fieldsReferencing[$target_type][$target_bundle] = [];
+      /** @var \Drupal\field\Entity\FieldConfig $config */
+      foreach (FieldConfig::loadMultiple($ids) as $config) {
+        $type = $config->getSetting('target_type');
+        $handler = $config->getSetting('handler_settings');
+        if ($type == $target_type) {
+          $bundles = !empty($handler['target_bundles']) ? array_keys($handler['target_bundles']) : [];
+          foreach ($bundles as $bundle) {
+            if ($bundle == $target_bundle) {
+              $this->fieldsReferencing[$target_type][$target_bundle][] = $config->id();
+              break;
+            }
+          }
+        }
+      }
+      unset($map, $ids);
+    }
+
+    return $this->fieldsReferencing[$target_type][$target_bundle];
+  }
+
+  /**
    * Builds field storage definitions for an entity type.
    *
    * @param string $entity_type_id
diff --git a/core/lib/Drupal/Core/Entity/EntityManagerInterface.php b/core/lib/Drupal/Core/Entity/EntityManagerInterface.php
index b3bda8b..5626fa6 100644
--- a/core/lib/Drupal/Core/Entity/EntityManagerInterface.php
+++ b/core/lib/Drupal/Core/Entity/EntityManagerInterface.php
@@ -143,6 +143,20 @@ public function getFieldMap();
   public function getFieldMapByFieldType($field_type);
 
   /**
+   * Returns a list of entity reference field configurations that are targeting
+   * a specific bundle.
+   *
+   * @param string $target_type
+   *   The entity type of target
+   * @param string $target_bundle
+   *   The bundle of target.
+   *
+   * @return string[]
+   *   A list of field IDs.
+   */
+  public function getFieldsReferencing($target_type, $target_bundle);
+
+  /**
    * Creates a new access control handler instance.
    *
    * @param string $entity_type
diff --git a/core/modules/entity_reference/entity_reference.module b/core/modules/entity_reference/entity_reference.module
index 889eaf3..7fd5fee 100644
--- a/core/modules/entity_reference/entity_reference.module
+++ b/core/modules/entity_reference/entity_reference.module
@@ -244,3 +244,42 @@ function entity_reference_create_field($entity_type, $bundle, $field_name, $fiel
   }
 }
 
+/**
+ * Implements hook_entity_bundle_rename().
+ */
+function entity_reference_entity_bundle_rename($entity_type, $bundle_old, $bundle_new) {
+  entity_reference_sync_fields($entity_type, $bundle_old, $bundle_new);
+}
+
+/**
+ * Implements hook_entity_bundle_delete().
+ */
+function entity_reference_entity_bundle_delete($entity_type, $bundle) {
+  entity_reference_sync_fields($entity_type, $bundle);
+}
+
+/**
+ * Sync bundle settings of entity reference fields targeting a bundle that is
+ * about to change.
+ *
+ * @param string $entity_type
+ *   The entity type of the bundle that is about to change.
+ * @param string $bundle
+ *   The bundle that is about to change.
+ * @param string|null $bundle_new
+ *   (optional) If provided the bundle has been renamed to this new name. If
+ *   omitted, the bundle has been deleted.
+ */
+function entity_reference_sync_fields($entity_type, $bundle, $bundle_new = NULL) {
+  $manager = \Drupal::entityManager();
+  $ids = $manager->getFieldsReferencing($entity_type, $bundle);
+
+  /** @var \Drupal\field\Entity\FieldConfig $field_config */
+  foreach (FieldConfig::loadMultiple($ids) as $field_config) {
+    if ($bundle_new) {
+      $field_config->settings['handler_settings']['target_bundles'][$bundle_new] = $bundle_new;
+    }
+    unset($field_config->settings['handler_settings']['target_bundles'][$bundle]);
+    $field_config->save();
+  }
+}
diff --git a/core/modules/entity_reference/src/Tests/EntityReferenceSettingsTest.php b/core/modules/entity_reference/src/Tests/EntityReferenceSettingsTest.php
new file mode 100644
index 0000000..5c6e851
--- /dev/null
+++ b/core/modules/entity_reference/src/Tests/EntityReferenceSettingsTest.php
@@ -0,0 +1,113 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\entity_reference\Tests\EntityReferenceSettingsTest.
+ */
+
+namespace Drupal\entity_reference\Tests;
+
+use Drupal\Component\Utility\Unicode;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\node\Entity\NodeType;
+use Drupal\simpletest\KernelTestBase;
+use Drupal\taxonomy\Entity\Vocabulary;
+
+/**
+ * Tests entity reference field settings.
+ *
+ * @group entity_reference
+ */
+class EntityReferenceSettingsTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['node', 'taxonomy', 'field', 'user', 'text', 'entity_reference'];
+
+  /**
+   * Testing node type.
+   *
+   * @var \Drupal\node\Entity\NodeType
+   */
+  protected $nodeType;
+
+  /**
+   * Testing vocabulary.
+   *
+   * @var \Drupal\taxonomy\Entity\Vocabulary
+   */
+  protected $vocabulary;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setup();
+
+    $this->installEntitySchema('node');
+    $this->installEntitySchema('taxonomy_term');
+
+    //
+    $this->nodeType = NodeType::create([
+      'type' => Unicode::strtolower($this->randomMachineName()),
+      'name' => $this->randomString(),
+    ]);
+    $this->nodeType->save();
+
+    $this->vocabulary = Vocabulary::create([
+      'vid' => Unicode::strtolower($this->randomMachineName()),
+      'name' => $this->randomString(),
+    ]);
+    $this->vocabulary->save();
+  }
+
+  /**
+   * Tests that bundle changes are mirrored in field definitions.
+   */
+  public function testSyncTargetBundleChanges() {
+    // Attach an entity reference field to $this->nodeType.
+    $field_name = Unicode::strtolower($this->randomMachineName());
+    $field_storage_config = FieldStorageConfig::create([
+      'type' => 'entity_reference',
+      'entity_type' => 'node',
+      'field_name' => $field_name,
+      'settings' => ['target_type' => 'taxonomy_term'],
+    ]);
+    $field_storage_config->save();
+    $field_config = FieldConfig::create([
+      'entity_type' => 'node',
+      'bundle' => $this->nodeType->id(),
+      'field_name' => $field_name,
+      'settings' => [
+        'handler_settings' => [
+          'target_bundles' => [
+            $this->vocabulary->id() => $this->vocabulary->id(),
+          ]
+        ],
+      ],
+    ]);
+    $field_config->save();
+
+    // Change the vocabulary vid.
+    $new_vid = Unicode::strtolower($this->randomMachineName());
+    $this->vocabulary->set('vid', $new_vid);
+    $this->vocabulary->save();
+
+    // Reload the field config and test the target vocabulary.
+    $field_config = FieldConfig::loadByName('node', $this->nodeType->id(), $field_name);
+    $handler_settings = $field_config->getSetting('handler_settings');
+    $vid = key($handler_settings['target_bundles']);
+    $this->assertIdentical($vid, $new_vid);
+
+    // Delete the vocabulary.
+    $this->vocabulary->delete();
+    // Reload and test again.
+    $field_config = FieldConfig::loadByName('node', $this->nodeType->id(), $field_name);
+    $handler_settings = $field_config->getSetting('handler_settings');
+    $bundles = !empty($handler_settings['target_bundles']) ? $handler_settings['target_bundles'] : [];
+    $this->assertTrue(empty($bundles));
+  }
+
+}