diff --git a/core/modules/aggregator/src/Controller/AggregatorController.php b/core/modules/aggregator/src/Controller/AggregatorController.php
index b49f3f5..b85ca2c 100644
--- a/core/modules/aggregator/src/Controller/AggregatorController.php
+++ b/core/modules/aggregator/src/Controller/AggregatorController.php
@@ -173,6 +173,10 @@ public function adminOverview() {
   public function pageLast() {
     $items = $this->entityManager()->getStorage('aggregator_item')->loadAll(20);
     $build = $this->buildPageList($items);
+
+    $config = $this->config('system.site');
+    $build['#cache']['tags'] = $config->getCacheTags();
+
     $build['#attached']['feed'][] = array('aggregator/rss', $this->config('system.site')->get('name') . ' ' . $this->t('aggregator'));
     return $build;
   }
diff --git a/core/modules/comment/src/CommentViewBuilder.php b/core/modules/comment/src/CommentViewBuilder.php
index b903250..fe27860 100644
--- a/core/modules/comment/src/CommentViewBuilder.php
+++ b/core/modules/comment/src/CommentViewBuilder.php
@@ -10,6 +10,7 @@
 use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
 use Drupal\Component\Utility\NestedArray;
 use Drupal\Core\Access\CsrfTokenGenerator;
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Entity\Display\EntityViewDisplayInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityManagerInterface;
@@ -154,7 +155,9 @@ public function buildComponents(array &$build, array $entities, array $displays,
       }
 
       $account = comment_prepare_author($entity);
-      if (\Drupal::config('user.settings')->get('signatures') && $account->getSignature()) {
+      $config = \Drupal::config('user.settings');
+      $build['#cache']['tags'] = Cache::mergeTags(isset($build['#cache']['tags']) ? $build['#cache']['tags'] : [],  $config->getCacheTags());
+      if ($config->get('signatures') && $account->getSignature()) {
         $build[$id]['signature'] = array(
           '#type' => 'processed_text',
           '#text' => $account->getSignature(),
diff --git a/core/modules/comment/src/Tests/CommentDefaultFormatterCacheTagsTest.php b/core/modules/comment/src/Tests/CommentDefaultFormatterCacheTagsTest.php
index 1a97e1b..fc4501d 100644
--- a/core/modules/comment/src/Tests/CommentDefaultFormatterCacheTagsTest.php
+++ b/core/modules/comment/src/Tests/CommentDefaultFormatterCacheTagsTest.php
@@ -108,6 +108,7 @@ public function testCacheTags() {
       'comment_view',
       'comment:' . $comment->id(),
       'config:filter.format.plain_text',
+      'config:user.settings',
       'user_view',
       'user:2',
     );
diff --git a/core/modules/contact/src/Controller/ContactController.php b/core/modules/contact/src/Controller/ContactController.php
index cffbf5a..c821e2c 100644
--- a/core/modules/contact/src/Controller/ContactController.php
+++ b/core/modules/contact/src/Controller/ContactController.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\contact\Controller;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Controller\ControllerBase;
 use Drupal\Core\Datetime\DateFormatter;
 use Drupal\Core\Flood\FloodInterface;
@@ -77,12 +78,13 @@ public function contactSitePage(ContactFormInterface $contact_form = NULL) {
     if (!$this->currentUser()->hasPermission('administer contact forms')) {
       $this->contactFloodControl();
     }
+    $config = $this->config('contact.settings');
 
     // Use the default form if no form has been passed.
     if (empty($contact_form)) {
       $contact_form = $this->entityManager()
         ->getStorage('contact_form')
-        ->load($this->config('contact.settings')->get('default_form'));
+        ->load($config->get('default_form'));
       // If there are no forms, do not display the form.
       if (empty($contact_form)) {
         if ($this->currentUser()->hasPermission('administer contact forms')) {
@@ -104,6 +106,7 @@ public function contactSitePage(ContactFormInterface $contact_form = NULL) {
 
     $form = $this->entityFormBuilder()->getForm($message);
     $form['#title'] = String::checkPlain($contact_form->label());
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
     return $form;
   }
 
diff --git a/core/modules/forum/src/Controller/ForumController.php b/core/modules/forum/src/Controller/ForumController.php
index 951e254..18d7325 100644
--- a/core/modules/forum/src/Controller/ForumController.php
+++ b/core/modules/forum/src/Controller/ForumController.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\forum\Controller;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Controller\ControllerBase;
 use Drupal\Core\Entity\EntityAccessControlHandlerInterface;
 use Drupal\Core\Entity\EntityStorageInterface;
@@ -190,6 +191,7 @@ protected function build($forums, TermInterface $term, $topics = array(), $paren
     if (empty($term->forum_container->value)) {
       $build['#attached']['feed'][] = array('taxonomy/term/' . $term->id() . '/feed', 'RSS - ' . $term->getName());
     }
+    $build['#cache']['tags'] = Cache::mergeTags(isset($build['#cache']['tags']) ? $build['#cache']['tags'] : [],  $config->getCacheTags());
 
     return [
       'action' => $this->buildActionLinks($config->get('vocabulary'), $term),
diff --git a/core/modules/search/src/Controller/SearchController.php b/core/modules/search/src/Controller/SearchController.php
index 4e79f79..6bba26a 100644
--- a/core/modules/search/src/Controller/SearchController.php
+++ b/core/modules/search/src/Controller/SearchController.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\search\Controller;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Config\ConfigFactory;
 use Drupal\Core\Controller\ControllerBase;
 use Drupal\search\SearchPageInterface;
@@ -89,7 +90,9 @@ public function view(Request $request, SearchPageInterface $entity) {
     if ($request->query->has('keys')) {
       if ($plugin->isSearchExecutable()) {
         // Log the search.
-        if ($this->config('search.settings')->get('logging')) {
+        $config = $this->config('search.settings');
+        $build['#cache']['tags'] = Cache::mergeTags(isset($build['#cache']['tags']) ? $build['#cache']['tags'] : [],  $config->getCacheTags());
+        if ($config->get('logging')) {
           $this->logger->notice('Searched %type for %keys.', array('%keys' => $keys, '%type' => $entity->label()));
         }
 
diff --git a/core/modules/system/src/Tests/Cache/PageCacheTagsIntegrationTest.php b/core/modules/system/src/Tests/Cache/PageCacheTagsIntegrationTest.php
index 3fc3e34..c9d11eb 100644
--- a/core/modules/system/src/Tests/Cache/PageCacheTagsIntegrationTest.php
+++ b/core/modules/system/src/Tests/Cache/PageCacheTagsIntegrationTest.php
@@ -93,6 +93,7 @@ function testPageCacheTags() {
       'config:system.menu.tools',
       'config:system.menu.footer',
       'config:system.menu.main',
+      'config:system.site',
     ));
 
     // Full node page 2.
@@ -124,6 +125,7 @@ function testPageCacheTags() {
       'config:system.menu.tools',
       'config:system.menu.footer',
       'config:system.menu.main',
+      'config:system.site',
     ));
   }
 
diff --git a/core/modules/user/src/AccountForm.php b/core/modules/user/src/AccountForm.php
index 7ed3cbd..3bb8779 100644
--- a/core/modules/user/src/AccountForm.php
+++ b/core/modules/user/src/AccountForm.php
@@ -74,6 +74,7 @@ public function form(array $form, FormStateInterface $form_state) {
     $account = $this->entity;
     $user = $this->currentUser();
     $config = \Drupal::config('user.settings');
+    $form['#cache']['tags'] = $config->getCacheTags();
 
     $language_interface = \Drupal::languageManager()->getCurrentLanguage();
     $register = $account->isAnonymous();
diff --git a/core/modules/user/src/Form/UserCancelForm.php b/core/modules/user/src/Form/UserCancelForm.php
index d3b6921..3223f14 100644
--- a/core/modules/user/src/Form/UserCancelForm.php
+++ b/core/modules/user/src/Form/UserCancelForm.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\user\Form;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Entity\ContentEntityConfirmFormBase;
 use Drupal\Core\Form\FormStateInterface;
 
@@ -76,6 +77,7 @@ public function getConfirmText() {
   public function buildForm(array $form, FormStateInterface $form_state) {
     $user = $this->currentUser();
     $this->cancelMethods = user_cancel_methods();
+    $config = $this->config('user.settings');
 
     // Display account cancellation method selection, if allowed.
     $admin_access = $user->hasPermission('administer users');
@@ -98,7 +100,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#description' => $this->t('When enabled, the user must confirm the account cancellation via email.'),
     );
     // Also allow to send account canceled notification mail, if enabled.
-    $default_notify = $this->config('user.settings')->get('notify.status_canceled');
+    $default_notify = $config->get('notify.status_canceled');
     $form['user_cancel_notify'] = array(
       '#type' => 'checkbox',
       '#title' => $this->t('Notify user when account is canceled'),
@@ -112,6 +114,8 @@ public function buildForm(array $form, FormStateInterface $form_state) {
 
     $form = parent::buildForm($form, $form_state);
 
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
+
     return $form;
   }
 
diff --git a/core/modules/user/src/Form/UserLoginForm.php b/core/modules/user/src/Form/UserLoginForm.php
index 999a7cd..a0c0876 100644
--- a/core/modules/user/src/Form/UserLoginForm.php
+++ b/core/modules/user/src/Form/UserLoginForm.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\user\Form;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Flood\FloodInterface;
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
@@ -78,13 +79,15 @@ public function getFormId() {
    * {@inheritdoc}
    */
   public function buildForm(array $form, FormStateInterface $form_state) {
+    $config = $this->config('system.site');
+
     // Display login form:
     $form['name'] = array(
       '#type' => 'textfield',
       '#title' => $this->t('Username'),
       '#size' => 60,
       '#maxlength' => USERNAME_MAX_LENGTH,
-      '#description' => $this->t('Enter your @s username.', array('@s' => $this->config('system.site')->get('name'))),
+      '#description' => $this->t('Enter your @s username.', array('@s' => $config->get('name'))),
       '#required' => TRUE,
       '#attributes' => array(
         'autocorrect' => 'off',
@@ -109,6 +112,8 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     $form['#validate'][] = '::validateAuthentication';
     $form['#validate'][] = '::validateFinal';
 
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
+
     return $form;
   }