diff --git a/core/lib/Drupal/Core/Block/BlockBase.php b/core/lib/Drupal/Core/Block/BlockBase.php
index ef127e99ef010e6106b59a77bb3d6bba1c5b5533..8c97809466099e6737b190d9769b3de7b2721ae4 100644
--- a/core/lib/Drupal/Core/Block/BlockBase.php
+++ b/core/lib/Drupal/Core/Block/BlockBase.php
@@ -8,7 +8,6 @@
 namespace Drupal\Core\Block;
 
 use Drupal\block\BlockInterface;
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Access\AccessResult;
 use Drupal\Core\Cache\CacheableDependencyInterface;
 use Drupal\Core\Form\FormStateInterface;
@@ -166,7 +165,7 @@ public function buildConfigurationForm(array $form, FormStateInterface $form_sta
     $form['admin_label'] = array(
       '#type' => 'item',
       '#title' => $this->t('Block description'),
-      '#markup' => SafeMarkup::checkPlain($definition['admin_label']),
+      '#plain_text' => $definition['admin_label'],
     );
     $form['label'] = array(
       '#type' => 'textfield',
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/EntityReferenceIdFormatter.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/EntityReferenceIdFormatter.php
index 69b5b9f5d6efa4a3aae7f212922da37e4940f2d7..3f7393907285577b85668a55663589fc80fcd379 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/EntityReferenceIdFormatter.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/EntityReferenceIdFormatter.php
@@ -8,7 +8,6 @@
 namespace Drupal\Core\Field\Plugin\Field\FieldFormatter;
 
 use Drupal\Core\Field\FieldItemListInterface;
-use Drupal\Component\Utility\SafeMarkup;
 
 /**
  * Plugin implementation of the 'entity reference ID' formatter.
@@ -33,7 +32,7 @@ public function viewElements(FieldItemListInterface $items) {
     foreach ($this->getEntitiesToView($items) as $delta => $entity) {
       if ($entity->id()) {
         $elements[$delta] = array(
-          '#markup' => SafeMarkup::checkPlain($entity->id()),
+          '#plain_text' => $entity->id(),
           // Create a cache tag entry for the referenced entity. In the case
           // that the referenced entity is deleted, the cache for referring
           // entities must be cleared.
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/EntityReferenceLabelFormatter.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/EntityReferenceLabelFormatter.php
index c362a80ec8856b03e992fd4d30bfb9af84628a82..68d28ad589bd0dd13d34b157e41ca5209a2b1df7 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/EntityReferenceLabelFormatter.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/EntityReferenceLabelFormatter.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Field\Plugin\Field\FieldFormatter;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Entity\Exception\UndefinedLinkTemplateException;
 use Drupal\Core\Field\FieldItemListInterface;
 use Drupal\Core\Form\FormStateInterface;
@@ -98,7 +97,7 @@ public function viewElements(FieldItemListInterface $items) {
         }
       }
       else {
-        $elements[$delta] = array('#markup' => SafeMarkup::checkPlain($label));
+        $elements[$delta] = array('#plain_text' => $label);
       }
       $elements[$delta]['#cache']['tags'] = $entity->getCacheTags();
     }
diff --git a/core/modules/block/src/BlockListBuilder.php b/core/modules/block/src/BlockListBuilder.php
index 43d7a1c7aadb2d8faa9ec393fe98135df6fa908e..c0a3b2e44af5e86fe08d3f331cc606ff70d2c731 100644
--- a/core/modules/block/src/BlockListBuilder.php
+++ b/core/modules/block/src/BlockListBuilder.php
@@ -9,7 +9,6 @@
 
 use Drupal\Component\Utility\Html;
 use Drupal\Component\Serialization\Json;
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Config\Entity\ConfigEntityListBuilder;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityStorageInterface;
@@ -261,7 +260,7 @@ protected function buildBlocksForm() {
             $form[$entity_id]['#attributes']['class'][] = 'js-block-placed';
           }
           $form[$entity_id]['info'] = array(
-            '#markup' => SafeMarkup::checkPlain($info['label']),
+            '#plain_text' => $info['label'],
             '#wrapper_attributes' => array(
               'class' => array('block'),
             ),
diff --git a/core/modules/block/src/Tests/BlockInterfaceTest.php b/core/modules/block/src/Tests/BlockInterfaceTest.php
index 5e8b54c5766d8a2b0a9d1736c0cfefd01c057faa..7215765cc26c166d08e1800776aa42cc5fddd95e 100644
--- a/core/modules/block/src/Tests/BlockInterfaceTest.php
+++ b/core/modules/block/src/Tests/BlockInterfaceTest.php
@@ -8,7 +8,6 @@
 namespace Drupal\block\Tests;
 
 use Drupal\Core\Cache\Cache;
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Form\FormState;
 use Drupal\simpletest\KernelTestBase;
 use Drupal\block\BlockInterface;
@@ -73,7 +72,7 @@ public function testBlockInterface() {
       'admin_label' => array(
         '#type' => 'item',
         '#title' => t('Block description'),
-        '#markup' => SafeMarkup::checkPlain($definition['admin_label']),
+        '#plain_text' => $definition['admin_label'],
       ),
       'label' => array(
         '#type' => 'textfield',
diff --git a/core/modules/contact/src/MessageViewBuilder.php b/core/modules/contact/src/MessageViewBuilder.php
index 24f58f566bb8e4b4b507095556a76db729fca23e..def70f9a51dd1b427f66fa804bc00aa9c10d56a4 100644
--- a/core/modules/contact/src/MessageViewBuilder.php
+++ b/core/modules/contact/src/MessageViewBuilder.php
@@ -9,7 +9,6 @@
 
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityViewBuilder;
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Mail\MailFormatHelper;
 use Drupal\Core\Render\Element;
 
@@ -42,7 +41,7 @@ public function buildComponents(array &$build, array $entities, array $displays,
         $build[$id]['message'] = array(
           '#type' => 'item',
           '#title' => t('Message'),
-          '#markup' => SafeMarkup::checkPlain($entity->getMessage()),
+          '#plain_text' => $entity->getMessage(),
         );
       }
     }
diff --git a/core/modules/content_translation/content_translation.admin.inc b/core/modules/content_translation/content_translation.admin.inc
index 5623f75988935288b5c2644c54cb6191b95f1d49..cea6b2ed37106250efff64dedd492e53dfadfea1 100644
--- a/core/modules/content_translation/content_translation.admin.inc
+++ b/core/modules/content_translation/content_translation.admin.inc
@@ -5,7 +5,6 @@
  * The content translation administration forms.
  */
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Config\Entity\ThirdPartySettingsInterface;
 use Drupal\Core\Entity\ContentEntityTypeInterface;
 use Drupal\Core\Entity\EntityTypeInterface;
@@ -216,10 +215,10 @@ function _content_translation_preprocess_language_content_settings_table(&$varia
               'bundle' => array(
                 '#prefix' => '<span class="visually-hidden">',
                 '#suffix' => '</span> ',
-                '#markup' => SafeMarkup::checkPlain($element[$bundle]['settings']['#label']),
+                '#plain_text' => $element[$bundle]['settings']['#label'],
               ),
               'field' => array(
-                '#markup' => SafeMarkup::checkPlain($field_element['#label']),
+                '#plain_text' => $field_element['#label'],
               ),
             ),
             'class' => array('field'),
@@ -250,15 +249,15 @@ function _content_translation_preprocess_language_content_settings_table(&$varia
                   'bundle' => array(
                     '#prefix' => '<span class="visually-hidden">',
                     '#suffix' => '</span> ',
-                    '#markup' => SafeMarkup::checkPlain($element[$bundle]['settings']['#label']),
+                    '#plain_text' => $element[$bundle]['settings']['#label'],
                   ),
                   'field' => array(
                     '#prefix' => '<span class="visually-hidden">',
                     '#suffix' => '</span> ',
-                    '#markup' => SafeMarkup::checkPlain($field_element['#label']),
+                    '#plain_text' => $field_element['#label'],
                   ),
                   'columns' => array(
-                    '#markup' => SafeMarkup::checkPlain($column_label),
+                    '#plain_text' => $column_label,
                   ),
                 ),
                 'class' => array('column'),
diff --git a/core/modules/field/src/Tests/EntityReference/EntityReferenceFormatterTest.php b/core/modules/field/src/Tests/EntityReference/EntityReferenceFormatterTest.php
index c89776445d163e06d0bf4b24a2709fe17e915c70..6bdbd26d91ff3401368e59d3bfd2ea9f683a65d0 100644
--- a/core/modules/field/src/Tests/EntityReference/EntityReferenceFormatterTest.php
+++ b/core/modules/field/src/Tests/EntityReference/EntityReferenceFormatterTest.php
@@ -174,7 +174,7 @@ public function testIdFormatter() {
     $formatter = 'entity_reference_entity_id';
     $build = $this->buildRenderArray([$this->referencedEntity, $this->unsavedReferencedEntity], $formatter);
 
-    $this->assertEqual($build[0]['#markup'], $this->referencedEntity->id(), sprintf('The markup returned by the %s formatter is correct for an item with a saved entity.', $formatter));
+    $this->assertEqual($build[0]['#plain_text'], $this->referencedEntity->id(), sprintf('The markup returned by the %s formatter is correct for an item with a saved entity.', $formatter));
     $this->assertEqual($build[0]['#cache']['tags'], $this->referencedEntity->getCacheTags(), sprintf('The %s formatter has the expected cache tags.', $formatter));
     $this->assertTrue(!isset($build[1]), sprintf('The markup returned by the %s formatter is correct for an item with a unsaved entity.', $formatter));
   }
@@ -244,7 +244,7 @@ public function testLabelFormatter() {
     // The second referenced entity is "autocreated", therefore not saved and
     // lacking any URL info.
     $expected_item_2 = array(
-      '#markup' => $this->unsavedReferencedEntity->label(),
+      '#plain_text' => $this->unsavedReferencedEntity->label(),
       '#cache' => array(
         'contexts' => [
           'user.permissions',
@@ -257,8 +257,8 @@ public function testLabelFormatter() {
 
     // Test with the 'link' setting set to FALSE.
     $build = $this->buildRenderArray([$this->referencedEntity, $this->unsavedReferencedEntity], $formatter, array('link' => FALSE));
-    $this->assertEqual($build[0]['#markup'], $this->referencedEntity->label(), sprintf('The markup returned by the %s formatter is correct for an item with a saved entity.', $formatter));
-    $this->assertEqual($build[1]['#markup'], $this->unsavedReferencedEntity->label(), sprintf('The markup returned by the %s formatter is correct for an item with a unsaved entity.', $formatter));
+    $this->assertEqual($build[0]['#plain_text'], $this->referencedEntity->label(), sprintf('The markup returned by the %s formatter is correct for an item with a saved entity.', $formatter));
+    $this->assertEqual($build[1]['#plain_text'], $this->unsavedReferencedEntity->label(), sprintf('The markup returned by the %s formatter is correct for an item with a unsaved entity.', $formatter));
 
     // Test an entity type that doesn't have any link templates, which means
     // \Drupal\Core\Entity\EntityInterface::urlInfo() will throw an exception
@@ -273,7 +273,7 @@ public function testLabelFormatter() {
     $referenced_entity_with_no_link_template->save();
 
     $build = $this->buildRenderArray([$referenced_entity_with_no_link_template], $formatter, array('link' => TRUE));
-    $this->assertEqual($build[0]['#markup'], $referenced_entity_with_no_link_template->label(), sprintf('The markup returned by the %s formatter is correct for an entity type with no valid link template.', $formatter));
+    $this->assertEqual($build[0]['#plain_text'], $referenced_entity_with_no_link_template->label(), sprintf('The markup returned by the %s formatter is correct for an entity type with no valid link template.', $formatter));
   }
 
   /**
diff --git a/core/modules/field_ui/src/Form/EntityDisplayFormBase.php b/core/modules/field_ui/src/Form/EntityDisplayFormBase.php
index b2275d0dcdae43ecc34c4ed8e009111f661afd70..e80707316c199ed2c16d09fccb5fb7e1faebd7bc 100644
--- a/core/modules/field_ui/src/Form/EntityDisplayFormBase.php
+++ b/core/modules/field_ui/src/Form/EntityDisplayFormBase.php
@@ -10,7 +10,6 @@
 use Drupal\Component\Plugin\Factory\DefaultFactory;
 use Drupal\Component\Plugin\PluginManagerBase;
 use Drupal\Component\Utility\Html;
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Entity\EntityForm;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityWithPluginCollectionInterface;
@@ -290,7 +289,7 @@ protected function buildFieldRow(FieldDefinitionInterface $field_definition, arr
         'defaultPlugin' => $this->getDefaultPlugin($field_definition->getType()),
       ),
       'human_name' => array(
-        '#markup' => SafeMarkup::checkPlain($label),
+        '#plain_text' => $label,
       ),
       'weight' => array(
         '#type' => 'textfield',
diff --git a/core/modules/image/src/Form/ImageStyleEditForm.php b/core/modules/image/src/Form/ImageStyleEditForm.php
index b07090b7c498d6a9cd35f109be0ad3296b233299..d17a12958c2fe3348fb92c13ff48b2fc349cb578 100644
--- a/core/modules/image/src/Form/ImageStyleEditForm.php
+++ b/core/modules/image/src/Form/ImageStyleEditForm.php
@@ -12,7 +12,6 @@
 use Drupal\Core\Url;
 use Drupal\image\ConfigurableImageEffectInterface;
 use Drupal\image\ImageEffectManager;
-use Drupal\Component\Utility\SafeMarkup;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -99,7 +98,7 @@ public function form(array $form, FormStateInterface $form_state) {
         '#tree' => FALSE,
         'data' => array(
           'label' => array(
-            '#markup' => SafeMarkup::checkPlain($effect->label()),
+            '#plain_text' => $effect->label(),
           ),
         ),
       );
diff --git a/core/modules/language/language.admin.inc b/core/modules/language/language.admin.inc
index 8c35c6bf848ba766642b9cbbf57accea50b83083..3f860de03ff537d9dacef2aa884fc86fa050abb6 100644
--- a/core/modules/language/language.admin.inc
+++ b/core/modules/language/language.admin.inc
@@ -5,7 +5,6 @@
  * Administration functions for language.module.
  */
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Render\Element;
 use Drupal\Core\Template\Attribute;
 use Drupal\Core\Url;
@@ -170,7 +169,7 @@ function template_preprocess_language_content_settings_table(&$variables) {
           'data' => array(
             '#prefix' => '<label>',
             '#suffix' => '</label>',
-            '#markup' => SafeMarkup::checkPlain($element[$bundle]['settings']['#label']),
+            '#plain_text' => $element[$bundle]['settings']['#label'],
           ),
           'class' => array('bundle'),
         ),
diff --git a/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php b/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php
index eb3804a25fc94d44038b2e8393948a40f39b3e76..ed80376ca223482d30710ca17b84b49f8bd7ae99 100644
--- a/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php
+++ b/core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\link\Plugin\Field\FieldFormatter;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Component\Utility\Unicode;
 use Drupal\Component\Utility\UrlHelper;
 use Drupal\Core\Field\FieldDefinitionInterface;
@@ -201,7 +200,7 @@ public function viewElements(FieldItemListInterface $items) {
 
       if (!empty($settings['url_only']) && !empty($settings['url_plain'])) {
         $element[$delta] = array(
-          '#markup' => SafeMarkup::checkPlain($link_title),
+          '#plain_text' => $link_title,
         );
 
         if (!empty($item->_attributes)) {
diff --git a/core/modules/rest/src/Plugin/views/display/RestExport.php b/core/modules/rest/src/Plugin/views/display/RestExport.php
index e3a587c245dda9fc908951f883f533154f7916fd..2d3a5b0fd77739dd67a79ce2565a3bcfd529ef05 100644
--- a/core/modules/rest/src/Plugin/views/display/RestExport.php
+++ b/core/modules/rest/src/Plugin/views/display/RestExport.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\rest\Plugin\views\display;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Cache\CacheableResponse;
 use Drupal\Core\Render\RenderContext;
@@ -318,11 +317,12 @@ public function render() {
     $this->view->element['#content_type'] = $this->getMimeType();
     $this->view->element['#cache_properties'][] = '#content_type';
 
-      // Wrap the output in a pre tag if this is for a live preview.
+    // Encode and wrap the output in a pre tag if this is for a live preview.
     if (!empty($this->view->live_preview)) {
       $build['#prefix'] = '<pre>';
-      $build['#markup'] = SafeMarkup::checkPlain($build['#markup']);
+      $build['#plain_text'] = $build['#markup'];
       $build['#suffix'] = '</pre>';
+      unset($build['#markup']);
     }
     elseif ($this->view->getRequest()->getFormat($this->view->element['#content_type']) !== 'html') {
       // This display plugin is primarily for returning non-HTML formats.
diff --git a/core/modules/rest/src/Tests/Views/StyleSerializerTest.php b/core/modules/rest/src/Tests/Views/StyleSerializerTest.php
index de114d43bae787d51ccc2cdbd9951b2f0d377d68..498942f6bf2254909e2f6f2a747dec33d0614a8d 100644
--- a/core/modules/rest/src/Tests/Views/StyleSerializerTest.php
+++ b/core/modules/rest/src/Tests/Views/StyleSerializerTest.php
@@ -480,16 +480,16 @@ public function testLivePreview() {
       $entities[] = $row->_entity;
     }
 
-    $expected = Html::escape($serializer->serialize($entities, 'json'));
+    $expected = $serializer->serialize($entities, 'json');
 
     $view->live_preview = TRUE;
 
     $build = $view->preview();
-    $rendered_json = $build['#markup'];
-    $this->assertEqual($rendered_json, $expected, 'Ensure the previewed json is escaped.');
+    $rendered_json = $build['#plain_text'];
+    $this->assertTrue(!isset($build['#markup']) && $rendered_json == $expected, 'Ensure the previewed json is escaped.');
     $view->destroy();
 
-    $expected = Html::escape($serializer->serialize($entities, 'xml'));
+    $expected = $serializer->serialize($entities, 'xml');
 
     // Change the request format to xml.
     $view->setDisplay('rest_export_1');
@@ -505,7 +505,7 @@ public function testLivePreview() {
 
     $this->executeView($view);
     $build = $view->preview();
-    $rendered_xml = $build['#markup'];
+    $rendered_xml = $build['#plain_text'];
     $this->assertEqual($rendered_xml, $expected, 'Ensure we preview xml when we change the request format.');
   }
 
diff --git a/core/modules/simpletest/src/Form/SimpletestTestForm.php b/core/modules/simpletest/src/Form/SimpletestTestForm.php
index aadc4a9fcdb59608accf03295c54c602a1157310..a46be86c1f7ade34277d67c5c34bbd74e605d408 100644
--- a/core/modules/simpletest/src/Form/SimpletestTestForm.php
+++ b/core/modules/simpletest/src/Form/SimpletestTestForm.php
@@ -8,7 +8,6 @@
 namespace Drupal\simpletest\Form;
 
 use Drupal\Component\Utility\SortArray;
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Render\RendererInterface;
@@ -179,7 +178,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
         );
         $form['tests'][$class]['description'] = array(
           '#prefix' => '<div class="description">',
-          '#markup' => SafeMarkup::checkPlain($info['description']),
+          '#plain_text' => $info['description'],
           '#suffix' => '</div>',
           '#wrapper_attributes' => array(
             'class' => array('simpletest-test-description', 'table-filter-text-source'),
diff --git a/core/modules/system/tests/modules/entity_test/src/EntityTestViewBuilder.php b/core/modules/system/tests/modules/entity_test/src/EntityTestViewBuilder.php
index 7cfec16449b56f2c55303bbf131720f0aff13fd4..e1042e958f6a3dc71aee0fd36cfbbebdf3cd2d1d 100644
--- a/core/modules/system/tests/modules/entity_test/src/EntityTestViewBuilder.php
+++ b/core/modules/system/tests/modules/entity_test/src/EntityTestViewBuilder.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\entity_test;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityViewBuilder;
 
@@ -36,7 +35,7 @@ public function buildComponents(array &$build, array $entities, array $displays,
     foreach ($entities as $id => $entity) {
       $build[$id]['label'] = array(
         '#weight' => -100,
-        '#markup' => SafeMarkup::checkPlain($entity->label()),
+        '#plain_text' => $entity->label(),
       );
       $build[$id]['separator'] = array(
         '#weight' => -150,
@@ -44,7 +43,7 @@ public function buildComponents(array &$build, array $entities, array $displays,
       );
       $build[$id]['view_mode'] = array(
         '#weight' => -200,
-        '#markup' => SafeMarkup::checkPlain($view_mode),
+        '#plain_text' => $view_mode,
       );
     }
   }
diff --git a/core/modules/system/tests/modules/entity_test/src/EntityTestViewBuilderOverriddenView.php b/core/modules/system/tests/modules/entity_test/src/EntityTestViewBuilderOverriddenView.php
index f4b719f684526924c43e032ce5c3ff91fa2017c9..8d443860ea783d9d4ca59cd8ac6a485c661331f4 100644
--- a/core/modules/system/tests/modules/entity_test/src/EntityTestViewBuilderOverriddenView.php
+++ b/core/modules/system/tests/modules/entity_test/src/EntityTestViewBuilderOverriddenView.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\entity_test;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Entity\EntityInterface;
 
 /**
@@ -20,7 +19,7 @@ class EntityTestViewBuilderOverriddenView extends EntityTestViewBuilder {
    */
   public function view(EntityInterface $entity, $view_mode = 'full', $langcode = NULL) {
     $build = [];
-    $build[$entity->id()]['#markup'] = SafeMarkup::checkPlain($entity->label());
+    $build[$entity->id()]['#plain_text'] = $entity->label();
     return $build;
   }
 
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestStoragePageCacheForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestStoragePageCacheForm.php
index 9f3ab5aeb300b192d2ed5837a5d3955b72a7f9de..865fd0e5268793800c42d13d5edf49d8bd159249 100644
--- a/core/modules/system/tests/modules/form_test/src/Form/FormTestStoragePageCacheForm.php
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestStoragePageCacheForm.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\form_test\Form;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
 
@@ -57,7 +56,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
    */
   function form_test_storage_page_cache_old_build_id($form) {
     if (isset($form['#build_id_old'])) {
-      $form['test_build_id_old']['#markup'] = SafeMarkup::checkPlain($form['#build_id_old']);
+      $form['test_build_id_old']['#plain_text'] = $form['#build_id_old'];
     }
     return $form;
   }
diff --git a/core/modules/views/src/Plugin/views/display/Feed.php b/core/modules/views/src/Plugin/views/display/Feed.php
index e4da10e25b7d81341aed954f80bb4c9a18d41f11..216a67592231e0da86399f474761feb902b6ddc5 100644
--- a/core/modules/views/src/Plugin/views/display/Feed.php
+++ b/core/modules/views/src/Plugin/views/display/Feed.php
@@ -99,7 +99,7 @@ public function preview() {
     if (!empty($this->view->live_preview)) {
       $output = array(
         '#prefix' => '<pre>',
-        '#markup' => SafeMarkup::checkPlain(drupal_render_root($output)),
+        '#plain_text' => drupal_render_root($output),
         '#suffix' => '</pre>',
       );
     }
diff --git a/core/modules/views_ui/src/Controller/ViewsUIController.php b/core/modules/views_ui/src/Controller/ViewsUIController.php
index bed5aaa882f26d3f799382aaaafdb903f038f5c9..2837508eaf01d69ee24f3dad4219d7df798c4086 100644
--- a/core/modules/views_ui/src/Controller/ViewsUIController.php
+++ b/core/modules/views_ui/src/Controller/ViewsUIController.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\views_ui\Controller;
 
-use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Controller\ControllerBase;
 use Drupal\Core\Url;
 use Drupal\views\ViewExecutable;
@@ -89,7 +88,7 @@ public function reportFields() {
     $header = array(t('Field name'), t('Used in'));
     $rows = array();
     foreach ($fields as $field_name => $views) {
-      $rows[$field_name]['data'][0] = SafeMarkup::checkPlain($field_name);
+      $rows[$field_name]['data'][0]['data']['#plain_text'] = $field_name;
       foreach ($views as $view) {
         $rows[$field_name]['data'][1][] = $this->l($view, new Url('entity.view.edit_form', array('view' => $view)));
       }
diff --git a/core/modules/views_ui/src/ViewListBuilder.php b/core/modules/views_ui/src/ViewListBuilder.php
index 16abf608b276bfaeaa42cf31dfc9f34d55a235c7..ece0acfdd3acb0ed701f7a80c9ad46619dd22df7 100644
--- a/core/modules/views_ui/src/ViewListBuilder.php
+++ b/core/modules/views_ui/src/ViewListBuilder.php
@@ -102,7 +102,7 @@ public function buildRow(EntityInterface $view) {
         ),
         'description' => array(
           'data' => array(
-            '#markup' => SafeMarkup::checkPlain($view->get('description')),
+            '#plain_text' => $view->get('description'),
           ),
           'class' => array('views-table-filter-text-source'),
         ),