diff --git a/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
index 1d69be2..d0d8ee0 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -149,6 +149,13 @@
   protected $validationRequired = FALSE;
 
   /**
+   * Whether to serialize the initialized fields when serializing the entity.
+   *
+   * @var bool
+   */
+  public $serializeComputedFieldValues = FALSE;
+
+  /**
    * {@inheritdoc}
    */
   public function __construct(array $values, $entity_type, $bundle = FALSE, $translations = array()) {
@@ -410,10 +417,17 @@ protected function clearTranslationCache() {
    * {@inheritdoc}
    */
   public function __sleep() {
+    if ($this->serializeComputedFieldValues) {
+      foreach ($this->referencedEntities() as $entity) {
+        if ($entity instanceof ContentEntityInterface) {
+          $entity->serializeComputedFieldValues = TRUE;
+        }
+      }
+    }
     // Get the values of instantiated field objects, only serialize the values.
     foreach ($this->fields as $name => $fields) {
       foreach ($fields as $langcode => $field) {
-        $this->values[$name][$langcode] = $field->getValue();
+        $this->values[$name][$langcode] = $field->getValue($this->serializeComputedFieldValues);
       }
     }
     $this->fields = array();
@@ -427,6 +441,14 @@ public function __sleep() {
   /**
    * {@inheritdoc}
    */
+  public function __wakeup() {
+    $this->serializeComputedFieldValues = FALSE;
+    parent::__wakeup();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function id() {
     return $this->getEntityKey('id');
   }
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
index 63bd90d..0fc514e 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -204,12 +204,12 @@ public function setValue($values, $notify = TRUE) {
   /**
    * {@inheritdoc}
    */
-  public function getValue() {
+  public function getValue($include_computed = FALSE) {
     $values = parent::getValue();
 
     // If there is an unsaved entity, return it as part of the field item values
     // to ensure idempotency of getValue() / setValue().
-    if ($this->hasNewEntity()) {
+    if ($include_computed || $this->hasNewEntity()) {
       $values['entity'] = $this->entity;
     }
     return $values;
diff --git a/core/lib/Drupal/Core/Form/FormCache.php b/core/lib/Drupal/Core/Form/FormCache.php
index 13e5430..a7196e8 100644
--- a/core/lib/Drupal/Core/Form/FormCache.php
+++ b/core/lib/Drupal/Core/Form/FormCache.php
@@ -4,6 +4,7 @@
 
 use Drupal\Component\Utility\Crypt;
 use Drupal\Core\Access\CsrfTokenGenerator;
+use Drupal\Core\Entity\ContentEntityFormInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\KeyValueStore\KeyValueExpirableFactoryInterface;
 use Drupal\Core\PageCache\RequestPolicyInterface;
@@ -192,9 +193,20 @@ public function setCache($form_build_id, $form, FormStateInterface $form_state)
       $this->keyValueExpirableFactory->get('form')->setWithExpire($form_build_id, $form, $expire);
     }
 
+    // If the form state contains a content entity form object then the entity
+    // should be cached together with the computed field values otherwise when
+    // unserialized the entity might differ from the initial entity used - e.g.
+    // when referenced entities have changed.
+    if (($form_object = $form_state->getFormObject()) && ($form_object instanceof ContentEntityFormInterface)) {
+      $entity = $form_object->getEntity();
+      $entity->serializeComputedFieldValues = TRUE;
+    }
     if ($data = $form_state->getCacheableArray()) {
       $this->keyValueExpirableFactory->get('form_state')->setWithExpire($form_build_id, $data, $expire);
     }
+    if (isset($entity)) {
+      $entity->serializeComputedFieldValues = FALSE;
+    }
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntitySerializationTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntitySerializationTest.php
new file mode 100644
index 0000000..747336c
--- /dev/null
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntitySerializationTest.php
@@ -0,0 +1,185 @@
+<?php
+
+namespace Drupal\KernelTests\Core\Entity;
+
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\field\Tests\EntityReference\EntityReferenceTestTrait;
+
+/**
+ * Tests entity serialization.
+ *
+ * @group Entity
+ */
+class EntitySerializationTest extends EntityKernelTestBase {
+
+  use EntityReferenceTestTrait;
+
+  /**
+   * The entity type used in this test.
+   *
+   * @var string
+   */
+  protected $entityType = 'entity_test';
+
+  /**
+   * The entity type that is being referenced.
+   *
+   * @var string
+   */
+  protected $referencedEntityType = 'entity_test_rev';
+
+  /**
+   * The bundle used in this test.
+   *
+   * @var string
+   */
+  protected $bundle = 'entity_test';
+
+  /**
+   * The name of the entity reference field used in this test.
+   *
+   * @var string
+   */
+  protected $fieldName = 'field_test';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $this->installEntitySchema('entity_test_rev');
+
+    // Create the entity reference fields.
+    $this->createEntityReferenceField(
+      $this->entityType,
+      $this->bundle,
+      $this->fieldName,
+      'Field test',
+      $this->referencedEntityType,
+      'default',
+      array('target_bundles' => array($this->bundle)),
+      FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED
+    );
+
+    $this->createEntityReferenceField(
+      $this->referencedEntityType,
+      $this->bundle,
+      $this->fieldName,
+      'Field test',
+      $this->referencedEntityType,
+      'default',
+      array('target_bundles' => array($this->bundle)),
+      FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED
+    );
+
+  }
+
+  /**
+   * Tests the regular entity serialization.
+   */
+  public function testEntitySerialization() {
+    $entity = $this->container->get('entity_type.manager')
+      ->getStorage($this->entityType)
+      ->create(['type' => $this->bundle, 'name' => 'test entity']);
+
+    $serialized_entity = serialize($entity);
+    $entity = unserialize($serialized_entity);
+
+    $this->assertEquals('test entity', $entity->label());
+  }
+
+  /**
+   * Tests the regular entity serialization with references.
+   */
+  public function testRegularEntitySerializationWithEntityReferences() {
+    $entity = $this->createEntity();
+
+    // Assert that the regular serialization will not serialize references.
+    $original_label = $entity->{$this->fieldName}->entity->label();
+    $entity->{$this->fieldName}->entity->name = 'test referenced entity changed';
+    $serialized_entity = serialize($entity);
+    $entity = unserialize($serialized_entity);
+    $this->assertEquals($original_label, $entity->{$this->fieldName}->entity->label());
+  }
+
+  /**
+   * Tests entity serialization with flag for serializing references.
+   */
+  public function testEntitySerializationWithSerializingEntityReferences() {
+    $entity = $this->createEntity();
+
+    // Assert that using the "serializeComputedFieldValues" flag the
+    // serialization will serialize references.
+    $original_label = $entity->{$this->fieldName}->entity->label();
+    $new_label = 'test referenced entity changed';
+    $this->assertNotEquals($original_label, $new_label);
+
+    $entity->{$this->fieldName}->entity->name = $new_label;
+    $entity->serializeComputedFieldValues = TRUE;
+    $serialized_entity = serialize($entity);
+    $entity = unserialize($serialized_entity);
+    $this->assertEquals($new_label, $entity->{$this->fieldName}->entity->label());
+    // Assert that after unserializing the entity the
+    // "serializeComputedFieldValues" flag is reset.
+    $this->assertTrue(empty($entity->serializeComputedFieldValues));
+    $this->assertTrue(empty($entity->{$this->fieldName}->entity->serializeComputedFieldValues));
+  }
+
+  /**
+   * Tests entity serialization with flag for serializing references - complex.
+   */
+  public function testEntitySerializationWithSerializingEntityReferencesDeeperStructure() {
+    $entity = $this->createEntity();
+
+    // Assert that using the "serializeComputedFieldValues" flag the
+    // serialization will serialize references on a deeper level as well.
+    $original_label_first_reference = $entity->{$this->fieldName}->entity->label();
+    $new_label_first_reference = 'test referenced entity changed';
+    $this->assertNotEquals($original_label_first_reference, $new_label_first_reference);
+    $original_label_second_reference = $entity->{$this->fieldName}->entity->{$this->fieldName}->entity->label();
+    $new_label_second_reference = 'test referenced entity 2 changed';
+    $this->assertNotEquals($original_label_second_reference, $new_label_second_reference);
+
+    $entity->{$this->fieldName}->entity->name = $new_label_first_reference;
+    $entity->{$this->fieldName}->entity->{$this->fieldName}->entity->name = $new_label_second_reference;
+    $entity->serializeComputedFieldValues = TRUE;
+    $serialized_entity = serialize($entity);
+    $entity = unserialize($serialized_entity);
+    $this->assertEquals($new_label_first_reference, $entity->{$this->fieldName}->entity->label());
+    $this->assertEquals($new_label_second_reference, $entity->{$this->fieldName}->entity->{$this->fieldName}->entity->label());
+    // Assert that after unserializing the entity the
+    // "serializeComputedFieldValues" flag is reset.
+    $this->assertTrue(empty($entity->serializeComputedFieldValues));
+    $this->assertTrue(empty($entity->{$this->fieldName}->entity->serializeComputedFieldValues));
+    $this->assertTrue(empty($entity->{$this->fieldName}->entity->{$this->fieldName}->entity->serializeComputedFieldValues));
+  }
+
+  /**
+   * Creates and returns an entity with references.
+   *
+   * @return \Drupal\Core\Entity\EntityTypeInterface
+   *   The entity object.
+   */
+  protected function createEntity() {
+    $referenced_entity = $this->container->get('entity_type.manager')
+      ->getStorage($this->referencedEntityType)
+      ->create(['type' => $this->bundle, 'name' => 'test referenced entity']);
+    $referenced_entity->save();
+
+    $referenced_entity_2 = $this->container->get('entity_type.manager')
+      ->getStorage($this->referencedEntityType)
+      ->create(['type' => $this->bundle, 'name' => 'test referenced entity 2']);
+    $referenced_entity_2->save();
+
+    $entity = $this->container->get('entity_type.manager')
+      ->getStorage($this->entityType)
+      ->create(['type' => $this->bundle, 'name' => 'test entity']);
+
+    $entity->{$this->fieldName}->entity = $referenced_entity;
+    $referenced_entity->{$this->fieldName}->entity = $referenced_entity_2;
+
+    return $entity;
+  }
+
+}