diff --git a/core/modules/entity_reference/entity_reference.module b/core/modules/entity_reference/entity_reference.module
index e44cc32..f613ba5 100644
--- a/core/modules/entity_reference/entity_reference.module
+++ b/core/modules/entity_reference/entity_reference.module
@@ -232,3 +232,100 @@ function entity_reference_create_instance($entity_type, $bundle, $field_name, $f
   }
 }
 
+/**
+ * Implements hook_entity_bundle_rename().
+ *
+ * Reflect bundle name changes in the definitions of existing entity reference
+ * field instances.
+ */
+function entity_reference_entity_bundle_rename($entity_type, $bundle_old, $bundle_new) {
+  // Compile a list of entity_reference field instances.
+  $ids = array();
+  foreach (\Drupal\field\Field::fieldInfo()->getFieldMap() as $type => $fields) {
+    foreach ($fields as $id => $info) {
+      if ($info['type'] == 'entity_reference') {
+        foreach ($info['bundles'] as $bundle) {
+          $ids[] = "$type.$bundle.$id";
+        }
+      }
+    }
+  }
+
+  foreach (entity_load_multiple('field_instance', $ids) as $instance) {
+    $handler_settings = $instance->getSetting('handler_settings');
+    if ($instance->getSetting('target_type') != $entity_type) {
+      // Not referencing the given entity type.
+      continue;
+    }
+    if (empty($handler_settings['target_bundles'])) {
+      // Instance is referencing all bundles.
+      continue;
+    }
+
+    $update_instance = FALSE;
+    foreach ($handler_settings['target_bundles'] as $delta => $bundle) {
+      if ($bundle == $bundle_old) {
+        $instance->settings['handler_settings']['target_bundles'][$delta] = $bundle_new;
+        $update_instance = TRUE;
+      }
+    }
+    if ($update_instance) {
+      $instance->save();
+    }
+  }
+}
+
+/**
+ * Implements hook_entity_bundle_delete().
+ *
+ * Reflect bundle deletions in the definitions of existing entity reference
+ * field instances.
+ */
+function entity_reference_entity_bundle_delete($entity_type, $bundle) {
+  // Compile a list of entity_reference field instances.
+  $ids = array();
+  foreach (\Drupal\field\Field::fieldInfo()->getFieldMap() as $type => $fields) {
+    foreach ($fields as $id => $info) {
+      if ($info['type'] == 'entity_reference') {
+        foreach ($info['bundles'] as $bundle) {
+          $ids[] = "$type.$bundle.$id";
+        }
+      }
+    }
+  }
+
+  // Iterate over all entity reference fields referencing the given entity type
+  // and warn the user if the deleted bundle was the only one referenced by the
+  // field.
+  foreach (entity_load_multiple('field_instance', $ids) as $instance) {
+    $handler_settings = $instance->getSetting('handler_settings');
+    if ($instance->getSetting('target_type') != $entity_type) {
+      // Not referencing the given entity type.
+      continue;
+    }
+    if (empty($handler_settings['target_bundles'])) {
+      // Instance is referencing all bundles.
+      continue;
+    }
+
+    $modified_instance = FALSE;
+    foreach ($handler_settings['target_bundles'] as $delta => $target_bundle) {
+      if ($target_bundle == $bundle) {
+        unset($handler_settings['target_bundles'][$delta]);
+        $modified_instance = TRUE;
+      }
+    }
+    if ($modified_instance) {
+      if (!empty($handler_settings['target_bundles'])) {
+        // Re-key the 'target_bundles' array.
+        $instance->settings['handler_settings']['target_bundles'] = array_values($handler_settings['target_bundles']);
+      }
+      else {
+        drupal_set_message(t('The %field field on the %bundle bundle was referencing the deleted bundle and is no longer filtering on bundles.', array('%field' => $instance->getLabel(), '%bundle' => $instance->targetBundle())), 'warning');
+      }
+
+      // Update the instance definition with the new target bundles.
+      $instance->save();
+    }
+  }
+}
diff --git a/core/modules/entity_reference/lib/Drupal/entity_reference/Tests/EntityReferenceFieldTest.php b/core/modules/entity_reference/lib/Drupal/entity_reference/Tests/EntityReferenceFieldTest.php
index 4119240..d085bfe 100644
--- a/core/modules/entity_reference/lib/Drupal/entity_reference/Tests/EntityReferenceFieldTest.php
+++ b/core/modules/entity_reference/lib/Drupal/entity_reference/Tests/EntityReferenceFieldTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\entity_reference\Tests;
 
+use Drupal\Component\Utility\Unicode;
 use Drupal\system\Tests\Entity\EntityUnitTestBase;
 use Drupal\field\Field;
 
@@ -117,4 +118,41 @@ public function testEntityReferenceFieldValidation() {
     // https://drupal.org/node/2064191 is fixed
   }
 
+  /**
+   * Tests that bundle changes are mirrored in field definitions.
+   */
+  public function testEntityReferenceFieldChangeMachineName() {
+    // Add several entries in the 'target_bundles' setting, to make sure that
+    // they all get updated.
+    $test_bundle_2 = Unicode::strtolower($this->randomName());
+    entity_test_create_bundle($test_bundle_2, NULL, $this->referencedEntityType);
+    $this->instance->settings['handler_settings']['target_bundles'] = array(
+      $test_bundle_2,
+      $this->bundle,
+    );
+    $this->instance->save();
+
+    // Change the machine name.
+    $test_bundle_2_new = Unicode::strtolower($this->randomName());
+    entity_test_rename_bundle($test_bundle_2, $test_bundle_2_new, $this->referencedEntityType);
+
+    // Check that the field instance settings have changed.
+    $instances = Field::fieldInfo()->getBundleInstances($this->entityType, $this->bundle);
+    $instance_settings = $instances[$this->fieldName]->getSetting('handler_settings');
+    $target_bundles = $instance_settings['target_bundles'];
+    $this->assertEqual($target_bundles[0], $test_bundle_2_new, 'Index 0: Machine name was updated correctly.');
+    $this->assertEqual($target_bundles[1], $this->bundle, 'Index 1: Machine name was left untouched.');
+    $this->assertEqual(count($target_bundles), 2, "The 'target_bundles' setting contains two elements.");
+
+    // Delete a bundle.
+    entity_test_delete_bundle($test_bundle_2_new, $this->referencedEntityType);
+
+    // Check that the field instance settings have changed.
+    $instances = Field::fieldInfo()->getBundleInstances($this->entityType, $this->bundle);
+    $instance_settings = $instances[$this->fieldName]->getSetting('handler_settings');
+    $target_bundles = $instance_settings['target_bundles'];
+    $this->assertEqual($target_bundles[0], $this->bundle, 'Index 0: The bundle that was not removed is still referenced.');
+    $this->assertEqual(count($target_bundles), 1, "The 'target_bundles' setting contains only one element.");
+  }
+
 }