diff --git a/core/modules/user/lib/Drupal/user/Entity/User.php b/core/modules/user/lib/Drupal/user/Entity/User.php
index 83e2103..22d98ac 100644
--- a/core/modules/user/lib/Drupal/user/Entity/User.php
+++ b/core/modules/user/lib/Drupal/user/Entity/User.php
@@ -114,6 +114,9 @@ public function preSave(EntityStorageInterface $storage) {
         \Drupal::service('user.data')->set('user', $this->id(), substr($key, 5), $this->{$key});
       }
     }
+
+    // Before saving the user, set changed time.
+    $this->changed->value = REQUEST_TIME;
   }
 
   /**
@@ -445,6 +448,13 @@ public function setUsername($username) {
   /**
    * {@inheritdoc}
    */
+  public function getChangedTime() {
+    return $this->get('changed')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     $fields['uid'] = FieldDefinition::create('integer')
       ->setLabel(t('User ID'))
@@ -529,6 +539,10 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ->setDescription(t('The email address used for initial account creation.'))
       ->setSetting('default_value', '');
 
+      $fields['changed'] = FieldDefinition::create('changed')
+          ->setLabel(t('Changed'))
+          ->setDescription(t('The time the user was most recently saved.'));
+
     // @todo Convert this to entity_reference_field, see
     // https://drupal.org/node/2044859.
     $fields['roles'] = FieldDefinition::create('string')
diff --git a/core/modules/user/lib/Drupal/user/UserInterface.php b/core/modules/user/lib/Drupal/user/UserInterface.php
index 4022179..68c2974 100644
--- a/core/modules/user/lib/Drupal/user/UserInterface.php
+++ b/core/modules/user/lib/Drupal/user/UserInterface.php
@@ -179,4 +179,11 @@ public function block();
    */
   public function getInitialEmail();
 
+  /**
+   * Returns the user modification timestamp.
+   *
+   * @return int
+   *   User modification timestamp.
+   */
+  public function getChangedTime();
 }
diff --git a/core/modules/user/user.install b/core/modules/user/user.install
index 97515a2..421102e 100644
--- a/core/modules/user/user.install
+++ b/core/modules/user/user.install
@@ -123,6 +123,12 @@ function user_schema() {
         'default' => '',
         'description' => 'E-mail address used for initial account creation.',
       ),
+      'changed' => array(
+        'description' => 'The Unix timestamp when the user was most recently saved.',
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+      ),
     ),
     'indexes' => array(
       'access' => array('access'),