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/block/src/BlockForm.php b/core/modules/block/src/BlockForm.php
index 3ff21f6..4a9c48c 100644
--- a/core/modules/block/src/BlockForm.php
+++ b/core/modules/block/src/BlockForm.php
@@ -10,6 +10,7 @@
 use Drupal\block\Event\BlockContextEvent;
 use Drupal\block\Event\BlockEvents;
 use Drupal\Component\Utility\Html;
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Entity\EntityForm;
 use Drupal\Core\Entity\EntityManagerInterface;
 use Drupal\Core\Executable\ExecutableManagerInterface;
@@ -108,10 +109,11 @@ public static function create(ContainerInterface $container) {
    */
   public function form(array $form, FormStateInterface $form_state) {
     $entity = $this->entity;
+    $config = $this->config('system.theme');
 
     // Store theme settings in $form_state for use below.
     if (!$theme = $entity->getTheme()) {
-      $theme = $this->config('system.theme')->get('default');
+      $theme = $config->get('default');
     }
     $form_state->set('block_theme', $theme);
 
@@ -176,6 +178,7 @@ public function form(array $form, FormStateInterface $form_state) {
       '#suffix' => '</div>',
     );
     $form['#attached']['library'][] = 'block/drupal.block.admin';
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
     return $form;
   }
 
diff --git a/core/modules/book/src/BookManager.php b/core/modules/book/src/BookManager.php
index cc6b8bb..6b7e8a2 100644
--- a/core/modules/book/src/BookManager.php
+++ b/core/modules/book/src/BookManager.php
@@ -317,7 +317,8 @@ public function getBookParents(array $item, array $parent = array()) {
    *   A parent selection form element.
    */
   protected function addParentSelectFormElements(array $book_link) {
-    if ($this->configFactory->get('book.settings')->get('override_parent_selector')) {
+    $config = $this->configFactory->get('book.settings');
+    if ($config->get('override_parent_selector')) {
       return array();
     }
     // Offer a message or a drop-down to choose a different parent page.
@@ -352,6 +353,7 @@ protected function addParentSelectFormElements(array $book_link) {
         '#suffix' => '</div>',
       );
     }
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
 
     return $form;
   }
diff --git a/core/modules/book/src/Form/BookSettingsForm.php b/core/modules/book/src/Form/BookSettingsForm.php
index 0db0dc5..143d995 100644
--- a/core/modules/book/src/Form/BookSettingsForm.php
+++ b/core/modules/book/src/Form/BookSettingsForm.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\book\Form;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Form\FormStateInterface;
 
@@ -51,6 +52,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#required' => TRUE,
     );
     $form['array_filter'] = array('#type' => 'value', '#value' => TRUE);
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
 
     return parent::buildForm($form, $form_state);
   }
diff --git a/core/modules/comment/src/CommentForm.php b/core/modules/comment/src/CommentForm.php
index fbb7442..e198154 100644
--- a/core/modules/comment/src/CommentForm.php
+++ b/core/modules/comment/src/CommentForm.php
@@ -10,6 +10,7 @@
 use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
 use Drupal\Component\Utility\String;
 use Drupal\Component\Utility\Unicode;
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Datetime\DrupalDateTime;
 use Drupal\Core\Entity\ContentEntityForm;
 use Drupal\Core\Entity\EntityManagerInterface;
@@ -78,6 +79,7 @@ public function form(array $form, FormStateInterface $form_state) {
     $entity = $this->entityManager->getStorage($comment->getCommentedEntityTypeId())->load($comment->getCommentedEntityId());
     $field_name = $comment->getFieldName();
     $field_definition = $this->entityManager->getFieldDefinitions($entity->getEntityTypeId(), $entity->bundle())[$comment->getFieldName()];
+    $config = $this->config('user.settings');
 
     // Use #comment-form as unique jump target, regardless of entity type.
     $form['#id'] = drupal_html_id('comment_form');
@@ -147,7 +149,7 @@ public function form(array $form, FormStateInterface $form_state) {
     );
     if ($is_admin) {
       $form['author']['name']['#title'] = $this->t('Authored by');
-      $form['author']['name']['#description'] = $this->t('Leave blank for %anonymous.', array('%anonymous' => $this->config('user.settings')->get('anonymous')));
+      $form['author']['name']['#description'] = $this->t('Leave blank for %anonymous.', array('%anonymous' => $config->get('anonymous')));
       $form['author']['name']['#autocomplete_route_name'] = 'user.autocomplete';
     }
     elseif ($this->currentUser->isAuthenticated()) {
@@ -157,7 +159,7 @@ public function form(array $form, FormStateInterface $form_state) {
       $form['author']['name']['#account'] = $this->currentUser;
     }
     elseif($this->currentUser->isAnonymous()) {
-      $form['author']['name']['#attributes']['data-drupal-default-value'] = $this->config('user.settings')->get('anonymous');
+      $form['author']['name']['#attributes']['data-drupal-default-value'] = $config->get('anonymous');
     }
 
     // Add author email and homepage fields depending on the current user.
@@ -207,6 +209,8 @@ public function form(array $form, FormStateInterface $form_state) {
       '#value' => ($comment->id() ? !$comment->getOwnerId() : $this->currentUser->isAnonymous()),
     );
 
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
+
     return parent::form($form, $form_state, $comment);
   }
 
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/ContactFormEditForm.php b/core/modules/contact/src/ContactFormEditForm.php
index 420be7d..d219519 100644
--- a/core/modules/contact/src/ContactFormEditForm.php
+++ b/core/modules/contact/src/ContactFormEditForm.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\contact;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Entity\EntityForm;
 use Drupal\Core\Entity\EntityTypeInterface;
@@ -34,7 +35,8 @@ public function form(array $form, FormStateInterface $form_state) {
     $form = parent::form($form, $form_state);
 
     $contact_form = $this->entity;
-    $default_form = $this->config('contact.settings')->get('default_form');
+    $config = $this->config('contact.settings');
+    $default_form = $config->get('default_form');
 
     $form['label'] = array(
       '#type' => 'textfield',
@@ -78,6 +80,7 @@ public function form(array $form, FormStateInterface $form_state) {
       '#default_value' => $default_form === $contact_form->id(),
     );
 
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
     return $form;
   }
 
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/language/src/Form/NegotiationSelectedForm.php b/core/modules/language/src/Form/NegotiationSelectedForm.php
index 57194f9..4b212b7 100644
--- a/core/modules/language/src/Form/NegotiationSelectedForm.php
+++ b/core/modules/language/src/Form/NegotiationSelectedForm.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\language\Form;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\Core\Form\ConfigFormBase;
@@ -41,6 +42,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#languages' => LanguageInterface::STATE_CONFIGURABLE | LanguageInterface::STATE_SITE_DEFAULT,
       '#default_value' => $config->get('selected_langcode'),
     );
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
 
     return parent::buildForm($form, $form_state);
   }
diff --git a/core/modules/language/src/Form/NegotiationUrlForm.php b/core/modules/language/src/Form/NegotiationUrlForm.php
index fa1cd3e..dea6aba 100644
--- a/core/modules/language/src/Form/NegotiationUrlForm.php
+++ b/core/modules/language/src/Form/NegotiationUrlForm.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\language\Form;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Language\LanguageManagerInterface;
@@ -131,6 +132,8 @@ public function buildForm(array $form, FormStateInterface $form_state) {
 
     $form_state->setRedirect('language.negotiation');
 
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
+
     return parent::buildForm($form, $form_state);
   }
 
diff --git a/core/modules/locale/src/Form/LocaleSettingsForm.php b/core/modules/locale/src/Form/LocaleSettingsForm.php
index 4ff2c33..958cb44 100644
--- a/core/modules/locale/src/Form/LocaleSettingsForm.php
+++ b/core/modules/locale/src/Form/LocaleSettingsForm.php
@@ -6,6 +6,7 @@
 
 namespace Drupal\locale\Form;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Form\FormStateInterface;
 
@@ -85,6 +86,8 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#description' => t('How to treat existing translations when automatically updating the interface translations.'),
     );
 
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
+
     return parent::buildForm($form, $form_state);
   }
 
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/taxonomy/src/TermForm.php b/core/modules/taxonomy/src/TermForm.php
index daa2868..e1d9720 100644
--- a/core/modules/taxonomy/src/TermForm.php
+++ b/core/modules/taxonomy/src/TermForm.php
@@ -22,6 +22,7 @@ public function form(array $form, FormStateInterface $form_state) {
     $term = $this->entity;
     $vocab_storage = $this->entityManager->getStorage('taxonomy_vocabulary');
     $vocabulary = $vocab_storage->load($term->bundle());
+    $config = $this->config('taxonomy.settings');
 
     $parent = array_keys(taxonomy_term_load_parents($term->id()));
     $form_state->set(['taxonomy', 'parent'], $parent);
@@ -38,7 +39,7 @@ public function form(array $form, FormStateInterface $form_state) {
     // numbers of items so we check for taxonomy.settings:override_selector
     // before loading the full vocabulary. Contrib modules can then intercept
     // before hook_form_alter to provide scalable alternatives.
-    if (!$this->config('taxonomy.settings')->get('override_selector')) {
+    if (!$config->get('override_selector')) {
       $parent = array_keys(taxonomy_term_load_parents($term->id()));
       $children = taxonomy_get_tree($vocabulary->id(), $term->id());
 
@@ -88,6 +89,8 @@ public function form(array $form, FormStateInterface $form_state) {
       '#value' => $term->id(),
     );
 
+    $form['#cache']['tags'] = Cache::mergeTags(isset($form['#cache']['tags']) ? $form['#cache']['tags'] : [],  $config->getCacheTags());
+
     return parent::form($form, $form_state, $term);
   }
 
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;
   }
 
diff --git a/core/modules/user/src/Form/UserPasswordResetForm.php b/core/modules/user/src/Form/UserPasswordResetForm.php
index 69b4588..303a21e 100644
--- a/core/modules/user/src/Form/UserPasswordResetForm.php
+++ b/core/modules/user/src/Form/UserPasswordResetForm.php
@@ -93,6 +93,8 @@ public function buildForm(array $form, FormStateInterface $form_state, AccountIn
       '#type' => 'submit',
       '#value' => $this->t('Log in'),
     );
+
+    $form['#cache']['tags'] = $this->config('user.settings')->getCacheTags();
     return $form;
   }