diff --git a/core/modules/system/config/schema/system.schema.yml b/core/modules/system/config/schema/system.schema.yml
index a6f61b68ed..e68bbae5a8 100644
--- a/core/modules/system/config/schema/system.schema.yml
+++ b/core/modules/system/config/schema/system.schema.yml
@@ -337,6 +337,9 @@ block.settings.system_menu_block:*:
     depth:
       type: integer
       label: 'Maximum number of levels'
+    expand_all_items:
+      type: boolean
+      label: 'Expand all items'
 
 block.settings.local_tasks_block:
   type: block_settings
diff --git a/core/modules/system/src/Plugin/Block/SystemMenuBlock.php b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
index a551ca64d3..72e4963923 100644
--- a/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
+++ b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
@@ -5,7 +5,9 @@
 use Drupal\Core\Block\BlockBase;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Menu\MenuActiveTrailInterface;
 use Drupal\Core\Menu\MenuLinkTreeInterface;
+use Drupal\Core\Menu\MenuTreeParameters;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
@@ -31,6 +33,13 @@ class SystemMenuBlock extends BlockBase implements ContainerFactoryPluginInterfa
    */
   protected $menuTree;
 
+  /**
+   * The active menu trail service.
+   *
+   * @var \Drupal\Core\Menu\MenuActiveTrailInterface
+   */
+  protected $menuActiveTrail;
+
   /**
    * Constructs a new SystemMenuBlock.
    *
@@ -42,10 +51,13 @@ class SystemMenuBlock extends BlockBase implements ContainerFactoryPluginInterfa
    *   The plugin implementation definition.
    * @param \Drupal\Core\Menu\MenuLinkTreeInterface $menu_tree
    *   The menu tree service.
+   * @param \Drupal\Core\Menu\MenuActiveTrailInterface $menu_active_trail
+   *   The active menu trail service.
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, MenuLinkTreeInterface $menu_tree) {
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MenuLinkTreeInterface $menu_tree, MenuActiveTrailInterface $menu_active_trail) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
     $this->menuTree = $menu_tree;
+    $this->menuActiveTrail = $menu_active_trail;
   }
 
   /**
@@ -56,7 +68,8 @@ public static function create(ContainerInterface $container, array $configuratio
       $configuration,
       $plugin_id,
       $plugin_definition,
-      $container->get('menu.link_tree')
+      $container->get('menu.link_tree'),
+      $container->get('menu.active_trail')
     );
   }
 
@@ -98,6 +111,12 @@ public function blockForm($form, FormStateInterface $form_state) {
       '#required' => TRUE,
     ];
 
+    $form['menu_levels']['expand_all_items'] = [
+      '#type' => 'checkbox',
+      '#title' => $this->t('Expand all menu items'),
+      '#default_value' => ![$config['expand_all_items']],
+    ];
+
     return $form;
   }
 
@@ -117,6 +136,7 @@ public static function processMenuLevelParents(&$element, FormStateInterface $fo
   public function blockSubmit($form, FormStateInterface $form_state) {
     $this->configuration['level'] = $form_state->getValue('level');
     $this->configuration['depth'] = $form_state->getValue('depth');
+    $this->configuration['expand_all_items'] = $form_state->getValue('expand_all_items');
   }
 
   /**
@@ -124,7 +144,14 @@ public function blockSubmit($form, FormStateInterface $form_state) {
    */
   public function build() {
     $menu_name = $this->getDerivativeId();
-    $parameters = $this->menuTree->getCurrentRouteMenuTreeParameters($menu_name);
+    if ($this->configuration['expand_all_items']) {
+      $parameters = new MenuTreeParameters();
+      $active_trail = $this->menuActiveTrail->getActiveTrailIds($menu_name);
+      $parameters->setActiveTrail($active_trail);
+    }
+    else {
+      $parameters = $this->menuTree->getCurrentRouteMenuTreeParameters($menu_name);
+    }
 
     // Adjust the menu tree parameters based on the block's configuration.
     $level = $this->configuration['level'];
@@ -173,6 +200,7 @@ public function defaultConfiguration() {
     return [
       'level' => 1,
       'depth' => 0,
+      'expand_all_items' => FALSE,
     ];
   }
 
diff --git a/core/modules/system/system.post_update.php b/core/modules/system/system.post_update.php
index ba8e798ca1..ee9fc3c887 100644
--- a/core/modules/system/system.post_update.php
+++ b/core/modules/system/system.post_update.php
@@ -178,3 +178,18 @@ function system_post_update_extra_fields(&$sandbox = NULL) {
 function system_post_update_states_clear_cache() {
   // Empty post-update hook.
 }
+
+/**
+ * Initialize 'expand_all_items' values to system_menu_block.
+ */
+function system_post_update_add_expand_all_items_key_in_system_menu_block() {
+  $block_storage = \Drupal::entityTypeManager()->getStorage('block');
+  $blocks = $block_storage->loadMultiple();
+  /** @var \Drupal\block\BlockInterface[] $blocks */
+  foreach ($blocks as $block) {
+    if (strpos($block->getPluginId(), 'system_menu_block:') !== FALSE) {
+      $block->set('settings.expand_all_items', FALSE);
+      $block->save();
+    }
+  }
+}
diff --git a/core/modules/system/tests/src/Kernel/Block/SystemMenuBlockTest.php b/core/modules/system/tests/src/Kernel/Block/SystemMenuBlockTest.php
index 7a6d6685e9..55709aaba1 100644
--- a/core/modules/system/tests/src/Kernel/Block/SystemMenuBlockTest.php
+++ b/core/modules/system/tests/src/Kernel/Block/SystemMenuBlockTest.php
@@ -282,6 +282,82 @@ public function testConfigLevelDepth() {
     }
   }
 
+  /**
+   * Tests the config expanded option.
+   */
+  public function testConfigExpanded() {
+
+    // Helper function to generate a configured block instance.
+    $place_block = function ($level, $depth) {
+      return $this->blockManager->createInstance('system_menu_block:' . $this->menu->id(), array(
+        'region' => 'footer',
+        'id' => 'machinename',
+        'theme' => 'stark',
+        'level' => $level,
+        'depth' => $depth,
+        'expand_all_items' => TRUE,
+      ));
+    };
+
+    // All the different block instances we're going to test.
+    $blocks = [
+      'all' => $place_block(1, 0),
+      'level_1_and_beyond' => $place_block(1, 0),
+      'level_2_and_beyond' => $place_block(2, 0),
+      'level_3_and_beyond' => $place_block(3, 0),
+    ];
+
+    $expectations = [];
+    $expectations['all'] = [
+      'test.example1' => [],
+      'test.example2' => [
+        'test.example3' => [
+          'test.example4' => [],
+        ],
+      ],
+      'test.example5' => [
+        'test.example7' => [],
+      ],
+      'test.example6' => [],
+      'test.example8' => [],
+    ];
+    $expectations['level_1_and_beyond'] = $expectations['all'];
+    $expectations['level_2_and_beyond'] = [
+      'test.example3' => [
+        'test.example4' => [],
+      ],
+      'test.example7' => [],
+    ];
+    $expectations['level_3_and_beyond'] = [
+      'test.example4' => [],
+    ];
+
+    // Scenario 1: test all block instances when there's no active trail.
+    foreach ($blocks as $id => $block) {
+      $block_build = $block->build();
+      $items = isset($block_build['#items']) ? $block_build['#items'] : [];
+      $this->assertSame($expectations[$id], $this->convertBuiltMenuToIdTree($items), 'Menu block "' . $id . '" with no active trail renders the expected tree.');
+    }
+
+    // Scenario 2: test all block instances when there's an active trail.
+    $route = $this->container->get('router.route_provider')->getRouteByName('example3');
+    $request = new Request();
+    $request->attributes->set(RouteObjectInterface::ROUTE_NAME, 'example3');
+    $request->attributes->set(RouteObjectInterface::ROUTE_OBJECT, $route);
+    $this->container->get('request_stack')->push($request);
+    // \Drupal\Core\Menu\MenuActiveTrail uses the cache collector pattern, which
+    // includes static caching. Since this second scenario simulates a second
+    // request, we must also simulate it for the MenuActiveTrail service, by
+    // clearing the cache collector's static cache.
+    \Drupal::service('menu.active_trail')->clear();
+
+    foreach ($blocks as $id => $block) {
+      $block_build = $block->build();
+      $items = isset($block_build['#items']) ? $block_build['#items'] : [];
+      $this->assertSame($expectations[$id], $this->convertBuiltMenuToIdTree($items), 'Menu block "' . $id . '" with an active trail renders the expected tree.');
+    }
+  }
+
   /**
    * Helper method to allow for easy menu link tree structure assertions.
    *
diff --git a/core/profiles/minimal/config/install/block.block.stark_admin.yml b/core/profiles/minimal/config/install/block.block.stark_admin.yml
index d4deb186da..4a30bafa0d 100644
--- a/core/profiles/minimal/config/install/block.block.stark_admin.yml
+++ b/core/profiles/minimal/config/install/block.block.stark_admin.yml
@@ -20,4 +20,5 @@ settings:
   label_display: visible
   level: 1
   depth: 0
+  expand_all_items: false
 visibility: {  }
diff --git a/core/profiles/minimal/config/install/block.block.stark_tools.yml b/core/profiles/minimal/config/install/block.block.stark_tools.yml
index 2b6d1d5e44..fa8e72462b 100644
--- a/core/profiles/minimal/config/install/block.block.stark_tools.yml
+++ b/core/profiles/minimal/config/install/block.block.stark_tools.yml
@@ -20,4 +20,5 @@ settings:
   label_display: visible
   level: 1
   depth: 0
+  expand_all_items: false
 visibility: {  }
diff --git a/core/profiles/standard/config/install/block.block.bartik_account_menu.yml b/core/profiles/standard/config/install/block.block.bartik_account_menu.yml
index 93cadc8bac..7999f9a5ed 100644
--- a/core/profiles/standard/config/install/block.block.bartik_account_menu.yml
+++ b/core/profiles/standard/config/install/block.block.bartik_account_menu.yml
@@ -20,4 +20,5 @@ settings:
   label_display: '0'
   level: 1
   depth: 1
+  expand_all_items: false
 visibility: {  }
diff --git a/core/profiles/standard/config/install/block.block.bartik_footer.yml b/core/profiles/standard/config/install/block.block.bartik_footer.yml
index a8623d11ea..3e689c96b7 100644
--- a/core/profiles/standard/config/install/block.block.bartik_footer.yml
+++ b/core/profiles/standard/config/install/block.block.bartik_footer.yml
@@ -20,4 +20,5 @@ settings:
   label_display: '0'
   level: 1
   depth: 0
+  expand_all_items: false
 visibility: {  }
diff --git a/core/profiles/standard/config/install/block.block.bartik_main_menu.yml b/core/profiles/standard/config/install/block.block.bartik_main_menu.yml
index dc7ebecb02..e2b601baf8 100644
--- a/core/profiles/standard/config/install/block.block.bartik_main_menu.yml
+++ b/core/profiles/standard/config/install/block.block.bartik_main_menu.yml
@@ -20,4 +20,5 @@ settings:
   label_display: '0'
   level: 1
   depth: 1
+  expand_all_items: false
 visibility: {  }
diff --git a/core/profiles/standard/config/install/block.block.bartik_tools.yml b/core/profiles/standard/config/install/block.block.bartik_tools.yml
index 5a2aae5cb3..8734d2e0c4 100644
--- a/core/profiles/standard/config/install/block.block.bartik_tools.yml
+++ b/core/profiles/standard/config/install/block.block.bartik_tools.yml
@@ -20,4 +20,5 @@ settings:
   label_display: visible
   level: 1
   depth: 0
+  expand_all_items: false
 visibility: {  }