diff --git a/core/composer.json b/core/composer.json
index 503704c..3ff4690 100644
--- a/core/composer.json
+++ b/core/composer.json
@@ -107,7 +107,6 @@
         "drupal/image": "self.version",
         "drupal/inline_form_errors": "self.version",
         "drupal/language": "self.version",
-        "drupal/layout_discovery": "self.version",
         "drupal/link": "self.version",
         "drupal/locale": "self.version",
         "drupal/minimal": "self.version",
diff --git a/core/core.services.yml b/core/core.services.yml
index 40c6a8a..bdfd347 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -643,6 +643,9 @@ services:
   plugin.manager.display_variant:
     class: Drupal\Core\Display\VariantManager
     parent: default_plugin_manager
+  plugin.manager.core.layout:
+    class: Drupal\Core\Layout\LayoutPluginManager
+    arguments: ['@container.namespaces', '@cache.discovery', '@module_handler', '@theme_handler']
   plugin.manager.queue_worker:
     class: Drupal\Core\Queue\QueueWorkerManager
     parent: default_plugin_manager
diff --git a/core/lib/Drupal/Core/Layout/Annotation/Layout.php b/core/lib/Drupal/Core/Layout/Annotation/Layout.php
index 1cb5ff0..4f30834 100644
--- a/core/lib/Drupal/Core/Layout/Annotation/Layout.php
+++ b/core/lib/Drupal/Core/Layout/Annotation/Layout.php
@@ -72,9 +72,9 @@ class Layout extends Plugin {
   /**
    * The template file to render this layout (relative to the 'path' given).
    *
-   * If specified, then the layout_discovery module will register the template
-   * with hook_theme() and the module or theme registering this layout does not
-   * need to do it.
+   * If specified, then the system module will register the template with
+   * hook_theme() and the module or theme registering this layout does not need
+   * to do it.
    *
    * @var string optional
    *
diff --git a/core/modules/field_layout/field_layout.info.yml b/core/modules/field_layout/field_layout.info.yml
index 237f18d..62f225a 100644
--- a/core/modules/field_layout/field_layout.info.yml
+++ b/core/modules/field_layout/field_layout.info.yml
@@ -4,5 +4,3 @@ description: 'Adds layout capabilities to the Field UI.'
 package: Core (Experimental)
 version: VERSION
 core: 8.x
-dependencies:
-  - layout_discovery
diff --git a/core/modules/field_layout/tests/src/Kernel/FieldLayoutEntityDisplayTest.php b/core/modules/field_layout/tests/src/Kernel/FieldLayoutEntityDisplayTest.php
index 3ca5e59..eddd54a 100644
--- a/core/modules/field_layout/tests/src/Kernel/FieldLayoutEntityDisplayTest.php
+++ b/core/modules/field_layout/tests/src/Kernel/FieldLayoutEntityDisplayTest.php
@@ -14,7 +14,7 @@ class FieldLayoutEntityDisplayTest extends KernelTestBase {
   /**
    * {@inheritdoc}
    */
-  protected static $modules = ['layout_discovery', 'field_layout', 'entity_test', 'field_layout_test', 'system'];
+  protected static $modules = ['field_layout', 'entity_test', 'field_layout_test', 'system'];
 
   /**
    * @covers ::preSave
@@ -68,7 +68,7 @@ public function testPreSave() {
     $expected['dependencies']['module'] = [
       'entity_test',
       'field_layout',
-      'layout_discovery',
+      'system',
     ];
     // A third party setting is added by the entity_test module.
     $expected['third_party_settings']['entity_test'] = ['foo' => 'bar'];
diff --git a/core/modules/layout_discovery/layout_discovery.info.yml b/core/modules/layout_discovery/layout_discovery.info.yml
deleted file mode 100644
index a9a4139..0000000
--- a/core/modules/layout_discovery/layout_discovery.info.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-name: 'Layout Discovery'
-type: module
-description: 'Provides a way for modules or themes to register layouts.'
-package: Core (Experimental)
-version: VERSION
-core: 8.x
diff --git a/core/modules/layout_discovery/layout_discovery.install b/core/modules/layout_discovery/layout_discovery.install
deleted file mode 100644
index e6c99e0..0000000
--- a/core/modules/layout_discovery/layout_discovery.install
+++ /dev/null
@@ -1,22 +0,0 @@
-<?php
-
-/**
- * @file
- * Install, update, and uninstall functions for the Layout Discovery module.
- */
-
-/**
- * Implements hook_requirements().
- */
-function layout_discovery_requirements($phase) {
-  $requirements = [];
-  if ($phase === 'install') {
-    if (\Drupal::moduleHandler()->moduleExists('layout_plugin')) {
-      $requirements['layout_discovery'] = [
-        'description' => t('Layout Discovery cannot be installed because the Layout Plugin module is installed and incompatible.'),
-        'severity' => REQUIREMENT_ERROR,
-      ];
-    }
-  }
-  return $requirements;
-}
diff --git a/core/modules/layout_discovery/layout_discovery.libraries.yml b/core/modules/layout_discovery/layout_discovery.libraries.yml
deleted file mode 100644
index aff70e0..0000000
--- a/core/modules/layout_discovery/layout_discovery.libraries.yml
+++ /dev/null
@@ -1,25 +0,0 @@
-onecol:
-  version: VERSION
-  css:
-    theme:
-      layouts/onecol/onecol.css: {}
-twocol_bricks:
-  version: VERSION
-  css:
-    theme:
-      layouts/twocol_bricks/twocol_bricks.css: {}
-twocol:
-  version: VERSION
-  css:
-    theme:
-      layouts/twocol/twocol.css: {}
-threecol_25_50_25:
-  version: VERSION
-  css:
-    theme:
-      layouts/threecol_25_50_25/threecol_25_50_25.css: {}
-threecol_33_34_33:
-  version: VERSION
-  css:
-    theme:
-      layouts/threecol_33_34_33/threecol_33_34_33.css: {}
diff --git a/core/modules/layout_discovery/layout_discovery.module b/core/modules/layout_discovery/layout_discovery.module
deleted file mode 100644
index 3cffee9..0000000
--- a/core/modules/layout_discovery/layout_discovery.module
+++ /dev/null
@@ -1,39 +0,0 @@
-<?php
-
-/**
- * @file
- * Provides hook implementations for Layout Discovery.
- */
-
-/**
- * Implements hook_help().
- */
-function layout_discovery_help($route_name) {
-  switch ($route_name) {
-    case 'help.page.layout_discovery':
-      $output = '<h3>' . t('About') . '</h3>';
-      $output .= '<p>' . t('Layout Discovery allows modules or themes to register layouts, and for other modules to list the available layouts and render them.') . '</p>';
-      $output .= '<p>' . t('For more information, see the <a href=":layout-discovery-documentation">online documentation for the Layout Discovery module</a>.', [':layout-discovery-documentation' => 'https://www.drupal.org/node/2619128']) . '</p>';
-      return $output;
-  }
-}
-
-/**
- * Implements hook_theme().
- */
-function layout_discovery_theme() {
-  return \Drupal::service('plugin.manager.core.layout')->getThemeImplementations();
-}
-
-/**
- * Prepares variables for layout templates.
- *
- * @param array &$variables
- *   An associative array containing:
- *   - content: An associative array containing the properties of the element.
- *     Properties used: #settings, #layout.
- */
-function template_preprocess_layout(&$variables) {
-  $variables['settings'] = isset($variables['content']['#settings']) ? $variables['content']['#settings'] : [];
-  $variables['layout'] = isset($variables['content']['#layout']) ? $variables['content']['#layout'] : [];
-}
diff --git a/core/modules/layout_discovery/layout_discovery.services.yml b/core/modules/layout_discovery/layout_discovery.services.yml
deleted file mode 100644
index 1e24db4..0000000
--- a/core/modules/layout_discovery/layout_discovery.services.yml
+++ /dev/null
@@ -1,4 +0,0 @@
-services:
-  plugin.manager.core.layout:
-    class: Drupal\Core\Layout\LayoutPluginManager
-    arguments: ['@container.namespaces', '@cache.discovery', '@module_handler', '@theme_handler']
diff --git a/core/modules/layout_discovery/layouts/onecol/layout--onecol.html.twig b/core/modules/system/layouts/onecol/layout--onecol.html.twig
similarity index 100%
copy from core/modules/layout_discovery/layouts/onecol/layout--onecol.html.twig
copy to core/modules/system/layouts/onecol/layout--onecol.html.twig
diff --git a/core/modules/layout_discovery/layouts/onecol/onecol.css b/core/modules/system/layouts/onecol/onecol.css
similarity index 100%
copy from core/modules/layout_discovery/layouts/onecol/onecol.css
copy to core/modules/system/layouts/onecol/onecol.css
diff --git a/core/modules/layout_discovery/layouts/threecol_25_50_25/layout--threecol-25-50-25.html.twig b/core/modules/system/layouts/threecol_25_50_25/layout--threecol-25-50-25.html.twig
similarity index 100%
copy from core/modules/layout_discovery/layouts/threecol_25_50_25/layout--threecol-25-50-25.html.twig
copy to core/modules/system/layouts/threecol_25_50_25/layout--threecol-25-50-25.html.twig
diff --git a/core/modules/layout_discovery/layouts/threecol_25_50_25/threecol_25_50_25.css b/core/modules/system/layouts/threecol_25_50_25/threecol_25_50_25.css
similarity index 100%
copy from core/modules/layout_discovery/layouts/threecol_25_50_25/threecol_25_50_25.css
copy to core/modules/system/layouts/threecol_25_50_25/threecol_25_50_25.css
diff --git a/core/modules/layout_discovery/layouts/threecol_33_34_33/layout--threecol-33-34-33.html.twig b/core/modules/system/layouts/threecol_33_34_33/layout--threecol-33-34-33.html.twig
similarity index 100%
copy from core/modules/layout_discovery/layouts/threecol_33_34_33/layout--threecol-33-34-33.html.twig
copy to core/modules/system/layouts/threecol_33_34_33/layout--threecol-33-34-33.html.twig
diff --git a/core/modules/layout_discovery/layouts/threecol_33_34_33/threecol_33_34_33.css b/core/modules/system/layouts/threecol_33_34_33/threecol_33_34_33.css
similarity index 100%
copy from core/modules/layout_discovery/layouts/threecol_33_34_33/threecol_33_34_33.css
copy to core/modules/system/layouts/threecol_33_34_33/threecol_33_34_33.css
diff --git a/core/modules/layout_discovery/layouts/twocol/layout--twocol.html.twig b/core/modules/system/layouts/twocol/layout--twocol.html.twig
similarity index 100%
copy from core/modules/layout_discovery/layouts/twocol/layout--twocol.html.twig
copy to core/modules/system/layouts/twocol/layout--twocol.html.twig
diff --git a/core/modules/layout_discovery/layouts/twocol/twocol.css b/core/modules/system/layouts/twocol/twocol.css
similarity index 100%
copy from core/modules/layout_discovery/layouts/twocol/twocol.css
copy to core/modules/system/layouts/twocol/twocol.css
diff --git a/core/modules/layout_discovery/layouts/twocol_bricks/layout--twocol-bricks.html.twig b/core/modules/system/layouts/twocol_bricks/layout--twocol-bricks.html.twig
similarity index 100%
copy from core/modules/layout_discovery/layouts/twocol_bricks/layout--twocol-bricks.html.twig
copy to core/modules/system/layouts/twocol_bricks/layout--twocol-bricks.html.twig
diff --git a/core/modules/layout_discovery/layouts/twocol_bricks/twocol_bricks.css b/core/modules/system/layouts/twocol_bricks/twocol_bricks.css
similarity index 100%
copy from core/modules/layout_discovery/layouts/twocol_bricks/twocol_bricks.css
copy to core/modules/system/layouts/twocol_bricks/twocol_bricks.css
diff --git a/core/modules/layout_discovery/layout_discovery.layouts.yml b/core/modules/system/system.layouts.yml
similarity index 87%
rename from core/modules/layout_discovery/layout_discovery.layouts.yml
rename to core/modules/system/system.layouts.yml
index 98b1ed6..a17d5e1 100644
--- a/core/modules/layout_discovery/layout_discovery.layouts.yml
+++ b/core/modules/system/system.layouts.yml
@@ -2,7 +2,7 @@ layout_onecol:
   label: 'One column'
   path: layouts/onecol
   template: layout--onecol
-  library: layout_discovery/onecol
+  library: system/drupal.layout.onecol
   category: 'Columns: 1'
   default_region: content
   regions:
@@ -13,7 +13,7 @@ layout_twocol:
   label: 'Two column'
   path: layouts/twocol
   template: layout--twocol
-  library: layout_discovery/twocol
+  library: system/drupal.layout.twocol
   category: 'Columns: 2'
   default_region: left
   regions:
@@ -30,7 +30,7 @@ layout_twocol_bricks:
   label: 'Two column bricks'
   path: layouts/twocol_bricks
   template: layout--twocol-bricks
-  library: layout_discovery/twocol_bricks
+  library: system/drupal.layout.twocol_bricks
   category: 'Columns: 2'
   default_region: middle
   regions:
@@ -53,7 +53,7 @@ layout_threecol_25_50_25:
   label: 'Three column 25/50/25'
   path: layouts/threecol_25_50_25
   template: layout--threecol-25-50-25
-  library: layout_discovery/threecol_25_50_25
+  library: system/drupal.layout.threecol_25_50_25
   category: 'Columns: 3'
   default_region: left
   regions:
@@ -72,7 +72,7 @@ layout_threecol_33_34_33:
   label: 'Three column 33/34/33'
   path: layouts/threecol_33_34_33
   template: layout--threecol-33-34-33
-  library: layout_discovery/threecol_33_34_33
+  library: system/drupal.layout.threecol_33_34_33
   category: 'Columns: 3'
   default_region: left
   regions:
diff --git a/core/modules/system/system.libraries.yml b/core/modules/system/system.libraries.yml
index 98eb283..e8e9365 100644
--- a/core/modules/system/system.libraries.yml
+++ b/core/modules/system/system.libraries.yml
@@ -80,3 +80,29 @@ drupal.system.date:
     - core/drupalSettings
     - core/jquery.once
     - core/drupal.form
+
+drupal.layout.onecol:
+  version: VERSION
+  css:
+    theme:
+      layouts/onecol/onecol.css: {}
+drupal.layout.twocol_bricks:
+  version: VERSION
+  css:
+    theme:
+      layouts/twocol_bricks/twocol_bricks.css: {}
+drupal.layout.twocol:
+  version: VERSION
+  css:
+    theme:
+      layouts/twocol/twocol.css: {}
+drupal.layout.threecol_25_50_25:
+  version: VERSION
+  css:
+    theme:
+      layouts/threecol_25_50_25/threecol_25_50_25.css: {}
+drupal.layout.threecol_33_34_33:
+  version: VERSION
+  css:
+    theme:
+      layouts/threecol_33_34_33/threecol_33_34_33.css: {}
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index a1a6b71..eb49824 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -268,7 +268,7 @@ function system_theme() {
       ],
       'template' => 'entity-add-list',
     ],
-  ]);
+  ], \Drupal::service('plugin.manager.core.layout')->getThemeImplementations());
 }
 
 /**
@@ -377,6 +377,19 @@ function template_preprocess_entity_add_list(&$variables) {
 }
 
 /**
+ * Prepares variables for layout templates.
+ *
+ * @param array &$variables
+ *   An associative array containing:
+ *   - content: An associative array containing the properties of the element.
+ *     Properties used: #settings, #layout.
+ */
+function template_preprocess_layout(&$variables) {
+  $variables['settings'] = isset($variables['content']['#settings']) ? $variables['content']['#settings'] : [];
+  $variables['layout'] = isset($variables['content']['#layout']) ? $variables['content']['#layout'] : [];
+}
+
+/**
  * @defgroup authorize Authorized operations
  * @{
  * Functions to run operations with elevated privileges via authorize.php.
diff --git a/core/modules/layout_discovery/templates/layout.html.twig b/core/modules/system/templates/layout.html.twig
similarity index 100%
copy from core/modules/layout_discovery/templates/layout.html.twig
copy to core/modules/system/templates/layout.html.twig
diff --git a/core/modules/layout_discovery/tests/src/Kernel/LayoutTest.php b/core/tests/Drupal/KernelTests/Core/Layout/LayoutTest.php
similarity index 97%
rename from core/modules/layout_discovery/tests/src/Kernel/LayoutTest.php
rename to core/tests/Drupal/KernelTests/Core/Layout/LayoutTest.php
index 9d4c446..a82a7f0 100644
--- a/core/modules/layout_discovery/tests/src/Kernel/LayoutTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Layout/LayoutTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\Tests\layout_discovery\Kernel;
+namespace Drupal\KernelTests\Core\Layout;
 
 use Drupal\Core\Form\FormState;
 use Drupal\KernelTests\KernelTestBase;
@@ -15,7 +15,7 @@ class LayoutTest extends KernelTestBase {
   /**
    * {@inheritdoc}
    */
-  public static $modules = ['system', 'layout_discovery', 'layout_test'];
+  public static $modules = ['system', 'layout_test'];
 
   /**
    * The layout plugin manager.
diff --git a/core/modules/layout_discovery/layouts/onecol/layout--onecol.html.twig b/core/themes/stable/layouts/onecol/layout--onecol.html.twig
similarity index 100%
rename from core/modules/layout_discovery/layouts/onecol/layout--onecol.html.twig
rename to core/themes/stable/layouts/onecol/layout--onecol.html.twig
diff --git a/core/modules/layout_discovery/layouts/onecol/onecol.css b/core/themes/stable/layouts/onecol/onecol.css
similarity index 100%
rename from core/modules/layout_discovery/layouts/onecol/onecol.css
rename to core/themes/stable/layouts/onecol/onecol.css
diff --git a/core/modules/layout_discovery/layouts/threecol_25_50_25/layout--threecol-25-50-25.html.twig b/core/themes/stable/layouts/threecol_25_50_25/layout--threecol-25-50-25.html.twig
similarity index 100%
rename from core/modules/layout_discovery/layouts/threecol_25_50_25/layout--threecol-25-50-25.html.twig
rename to core/themes/stable/layouts/threecol_25_50_25/layout--threecol-25-50-25.html.twig
diff --git a/core/modules/layout_discovery/layouts/threecol_25_50_25/threecol_25_50_25.css b/core/themes/stable/layouts/threecol_25_50_25/threecol_25_50_25.css
similarity index 100%
rename from core/modules/layout_discovery/layouts/threecol_25_50_25/threecol_25_50_25.css
rename to core/themes/stable/layouts/threecol_25_50_25/threecol_25_50_25.css
diff --git a/core/modules/layout_discovery/layouts/threecol_33_34_33/layout--threecol-33-34-33.html.twig b/core/themes/stable/layouts/threecol_33_34_33/layout--threecol-33-34-33.html.twig
similarity index 100%
rename from core/modules/layout_discovery/layouts/threecol_33_34_33/layout--threecol-33-34-33.html.twig
rename to core/themes/stable/layouts/threecol_33_34_33/layout--threecol-33-34-33.html.twig
diff --git a/core/modules/layout_discovery/layouts/threecol_33_34_33/threecol_33_34_33.css b/core/themes/stable/layouts/threecol_33_34_33/threecol_33_34_33.css
similarity index 100%
rename from core/modules/layout_discovery/layouts/threecol_33_34_33/threecol_33_34_33.css
rename to core/themes/stable/layouts/threecol_33_34_33/threecol_33_34_33.css
diff --git a/core/modules/layout_discovery/layouts/twocol/layout--twocol.html.twig b/core/themes/stable/layouts/twocol/layout--twocol.html.twig
similarity index 100%
rename from core/modules/layout_discovery/layouts/twocol/layout--twocol.html.twig
rename to core/themes/stable/layouts/twocol/layout--twocol.html.twig
diff --git a/core/modules/layout_discovery/layouts/twocol/twocol.css b/core/themes/stable/layouts/twocol/twocol.css
similarity index 100%
rename from core/modules/layout_discovery/layouts/twocol/twocol.css
rename to core/themes/stable/layouts/twocol/twocol.css
diff --git a/core/modules/layout_discovery/layouts/twocol_bricks/layout--twocol-bricks.html.twig b/core/themes/stable/layouts/twocol_bricks/layout--twocol-bricks.html.twig
similarity index 100%
rename from core/modules/layout_discovery/layouts/twocol_bricks/layout--twocol-bricks.html.twig
rename to core/themes/stable/layouts/twocol_bricks/layout--twocol-bricks.html.twig
diff --git a/core/modules/layout_discovery/layouts/twocol_bricks/twocol_bricks.css b/core/themes/stable/layouts/twocol_bricks/twocol_bricks.css
similarity index 100%
rename from core/modules/layout_discovery/layouts/twocol_bricks/twocol_bricks.css
rename to core/themes/stable/layouts/twocol_bricks/twocol_bricks.css
diff --git a/core/modules/layout_discovery/templates/layout.html.twig b/core/themes/stable/templates/layout/layout.html.twig
similarity index 100%
rename from core/modules/layout_discovery/templates/layout.html.twig
rename to core/themes/stable/templates/layout/layout.html.twig