diff --git a/core/lib/Drupal/Core/Menu/MenuTreeParameters.php b/core/lib/Drupal/Core/Menu/MenuTreeParameters.php
index 2ea493d..472f15d 100644
--- a/core/lib/Drupal/Core/Menu/MenuTreeParameters.php
+++ b/core/lib/Drupal/Core/Menu/MenuTreeParameters.php
@@ -138,6 +138,16 @@ public function addExpandedParents(array $parents) {
   }
 
   /**
+   * Empty the expanded parents variable, to expand all items of the menu tree.
+   *
+   * @return $this
+   */
+  public function emptyExpandedParents() {
+    $this->expandedParents = array();
+    return $this;
+  }
+
+  /**
    * Sets the active trail IDs used to set the inActiveTrail property.
    *
    * @param string[] $active_trail
diff --git a/core/modules/menu_ui/src/Tests/MenuTest.php b/core/modules/menu_ui/src/Tests/MenuTest.php
index d88911a..3311ac6 100644
--- a/core/modules/menu_ui/src/Tests/MenuTest.php
+++ b/core/modules/menu_ui/src/Tests/MenuTest.php
@@ -150,6 +150,28 @@ function testMenu() {
   }
 
   /**
+   * Test the "expand all items" feature.
+   */
+  public function testExpandAllItems() {
+    $this->drupalLogin($this->adminUser);
+    $menu = $this->addCustomMenu();
+    $node = $this->drupalCreateNode(array('type' => 'article'));
+    $item1 = $this->addMenuLink('', '/node/' . $node->id(), $menu->id(), FALSE);
+    $item2 = $this->addMenuLink($item1->getPluginId(), '/node/' . $node->id(), $menu->id(), FALSE);
+    $item3 = $this->addMenuLink($item1->getPluginId(), '/node/' . $node->id(), $menu->id());
+    $block_id = $this->blockPlacements[$menu->id()];
+    $this->drupalGet('admin/structure/block/manage/' . $block_id);
+    $this->drupalPostForm(NULL, [
+      'settings[depth]' => 2,
+      'settings[level]' => 1,
+      'settings[expand_all_items]' => 1,
+    ], t('Save block'));
+    $this->verifyMenuLink($item1, $node);
+    $this->verifyMenuLink($item2, $node);
+    $this->verifyMenuLink($item3, $node);
+  }
+
+  /**
    * Adds a custom menu using CRUD functions.
    */
   function addCustomMenuCRUD() {
diff --git a/core/modules/system/config/schema/system.schema.yml b/core/modules/system/config/schema/system.schema.yml
index e34d375..0e58508 100644
--- a/core/modules/system/config/schema/system.schema.yml
+++ b/core/modules/system/config/schema/system.schema.yml
@@ -338,6 +338,9 @@ 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 83a2f85..464a95e 100644
--- a/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
+++ b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
@@ -112,6 +112,13 @@ public function blockForm($form, FormStateInterface $form_state) {
       '#required' => TRUE,
     );
 
+    $form['expand_all_items'] = array(
+      '#type' => 'checkbox',
+      '#title' => $this->t('Expand all items in this tree'),
+      '#default_value' => !empty($config['expand_all_items']),
+      '#description' => $this->t('Expand all items of this menu tree to show all items including the active trail.'),
+    );
+
     return $form;
   }
 
@@ -131,6 +138,7 @@ 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');
   }
 
   /**
@@ -151,6 +159,9 @@ public function build() {
     if ($depth > 0) {
       $parameters->setMaxDepth(min($level + $depth - 1, $this->menuTree->maxDepth()));
     }
+    if (!empty($this->configuration['expand_all_items'])) {
+      $parameters->emptyExpandedParents();
+    }
 
     $tree = $this->menuTree->load($menu_name, $parameters);
     $manipulators = array(
@@ -168,6 +179,7 @@ public function defaultConfiguration() {
     return [
       'level' => 1,
       'depth' => 0,
+      'expand_all_items' => FALSE,
     ];
   }