diff --git a/core/modules/views/src/Plugin/views/style/StylePluginBase.php b/core/modules/views/src/Plugin/views/style/StylePluginBase.php
index 719ee58e49412cd9a0d9cf51679666f826e63d7e..148e053c360995214d45fef3643b7a8d08af0d4d 100644
--- a/core/modules/views/src/Plugin/views/style/StylePluginBase.php
+++ b/core/modules/views/src/Plugin/views/style/StylePluginBase.php
@@ -482,9 +482,17 @@ public function render() {
    * grouping.
    *
    * @param $sets
-   *   Array containing the grouping sets to render.
+   *   An array keyed by group content containing the grouping sets to render.
+   *   Each set contains the following associative array:
+   *   - group: The group content.
+   *   - level: The hierarchical level of the grouping.
+   *   - rows: The result rows to be rendered in this group..
    * @param $level
-   *   Integer indicating the hierarchical level of the grouping.
+   *   (deprecated) This is no longer used and will be removed in Drupal 9. The
+   *   'level' key in $sets is used to indicate the hierarchical level of the
+   *   grouping.
+   *
+   * @todo Remove the $level parameter in https://www.drupal.org/node/2633890.
    *
    * @return string
    *   Rendered output of given grouping sets.
@@ -493,16 +501,16 @@ public function renderGroupingSets($sets, $level = 0) {
     $output = array();
     $theme_functions = $this->view->buildThemeFunctions($this->groupingTheme);
     foreach ($sets as $set) {
+      $level = isset($set['level']) ? $set['level'] : 0;
+
       $row = reset($set['rows']);
       // Render as a grouping set.
       if (is_array($row) && isset($row['group'])) {
-        $output[] = array(
+        $single_output = array(
           '#theme' => $theme_functions,
           '#view' => $this->view,
           '#grouping' => $this->options['grouping'][$level],
-          '#grouping_level' => $level,
           '#rows' => $set['rows'],
-          '#title' => $set['group'],
         );
       }
       // Render as a record set.
@@ -515,10 +523,11 @@ public function renderGroupingSets($sets, $level = 0) {
         }
 
         $single_output = $this->renderRowGroup($set['rows']);
-        $single_output['#grouping_level'] = $level;
-        $single_output['#title'] = $set['group'];
-        $output[] = $single_output;
       }
+
+      $single_output['#grouping_level'] = $level;
+      $single_output['#title'] = $set['group'];
+      $output[] = $single_output;
     }
     unset($this->view->row_index);
     return $output;
@@ -546,9 +555,11 @@ public function renderGroupingSets($sets, $level = 0) {
    *   array(
    *     'grouping_field_1:grouping_1' => array(
    *       'group' => 'grouping_field_1:content_1',
+   *       'level' => 0,
    *       'rows' => array(
    *         'grouping_field_2:grouping_a' => array(
    *           'group' => 'grouping_field_2:content_a',
+   *           'level' => 1,
    *           'rows' => array(
    *             $row_index_1 => $row_1,
    *             $row_index_2 => $row_2,
@@ -580,7 +591,7 @@ public function renderGrouping($records, $groupings = array(), $group_rendered =
         // hierarchically positioned set where the current row belongs to.
         // While iterating, parent groups, that do not exist yet, are added.
         $set = &$sets;
-        foreach ($groupings as $info) {
+        foreach ($groupings as $level => $info) {
           $field = $info['field'];
           $rendered = isset($info['rendered']) ? $info['rendered'] : $group_rendered;
           $rendered_strip = isset($info['rendered_strip']) ? $info['rendered_strip'] : FALSE;
@@ -613,6 +624,7 @@ public function renderGrouping($records, $groupings = array(), $group_rendered =
           // Create the group if it does not exist yet.
           if (empty($set[$grouping])) {
             $set[$grouping]['group'] = $group_content;
+            $set[$grouping]['level'] = $level;
             $set[$grouping]['rows'] = array();
           }
 
diff --git a/core/modules/views/src/Tests/Plugin/StyleTest.php b/core/modules/views/src/Tests/Plugin/StyleTest.php
index 68ce82eb10342d22f015e73013e660e308f0412e..c44eda6fa9a74206ab3e56bb041193738faac5d9 100644
--- a/core/modules/views/src/Tests/Plugin/StyleTest.php
+++ b/core/modules/views/src/Tests/Plugin/StyleTest.php
@@ -149,8 +149,10 @@ function _testGrouping($stripped = FALSE) {
     $expected = array();
     $expected['Job: Singer'] = array();
     $expected['Job: Singer']['group'] = 'Job: Singer';
+    $expected['Job: Singer']['level'] = 0;
     $expected['Job: Singer']['rows']['Age: 25'] = array();
     $expected['Job: Singer']['rows']['Age: 25']['group'] = 'Age: 25';
+    $expected['Job: Singer']['rows']['Age: 25']['level'] = 1;
     $expected['Job: Singer']['rows']['Age: 25']['rows'][0] = new ResultRow(['index' => 0]);
     $expected['Job: Singer']['rows']['Age: 25']['rows'][0]->views_test_data_name = 'John';
     $expected['Job: Singer']['rows']['Age: 25']['rows'][0]->views_test_data_job = 'Singer';
@@ -158,6 +160,7 @@ function _testGrouping($stripped = FALSE) {
     $expected['Job: Singer']['rows']['Age: 25']['rows'][0]->views_test_data_id = '1';
     $expected['Job: Singer']['rows']['Age: 27'] = array();
     $expected['Job: Singer']['rows']['Age: 27']['group'] = 'Age: 27';
+    $expected['Job: Singer']['rows']['Age: 27']['level'] = 1;
     $expected['Job: Singer']['rows']['Age: 27']['rows'][1] = new ResultRow(['index' => 1]);
     $expected['Job: Singer']['rows']['Age: 27']['rows'][1]->views_test_data_name = 'George';
     $expected['Job: Singer']['rows']['Age: 27']['rows'][1]->views_test_data_job = 'Singer';
@@ -165,8 +168,10 @@ function _testGrouping($stripped = FALSE) {
     $expected['Job: Singer']['rows']['Age: 27']['rows'][1]->views_test_data_id = '2';
     $expected['Job: Drummer'] = array();
     $expected['Job: Drummer']['group'] = 'Job: Drummer';
+    $expected['Job: Drummer']['level'] = 0;
     $expected['Job: Drummer']['rows']['Age: 28'] = array();
     $expected['Job: Drummer']['rows']['Age: 28']['group'] = 'Age: 28';
+    $expected['Job: Drummer']['rows']['Age: 28']['level'] = 1;
     $expected['Job: Drummer']['rows']['Age: 28']['rows'][2] = new ResultRow(['index' => 2]);
     $expected['Job: Drummer']['rows']['Age: 28']['rows'][2]->views_test_data_name = 'Ringo';
     $expected['Job: Drummer']['rows']['Age: 28']['rows'][2]->views_test_data_job = 'Drummer';