diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 7bfa55c..4e9803a 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -514,10 +514,10 @@ function watchdog_exception($type, Exception $exception, $message = NULL, $varia
  * drupal_set_message(t('An error occurred and processing did not complete.'), 'error');
  * @endcode
  *
- * @param string $message
+ * @param array|string $message
  *   (optional) The translated message to be displayed to the user. For
  *   consistency with other messages, it should begin with a capital letter and
- *   end with a period.
+ *   end with a period or a render array.
  * @param string $type
  *   (optional) The message's type. Defaults to 'status'. These values are
  *   supported:
@@ -561,6 +561,11 @@ function drupal_set_message($message = NULL, $type = 'status', $repeat = FALSE)
       $_SESSION['messages'][$type] = array();
     }
 
+    // When provided a render array, render it before storing it on the session.
+    if (is_array($message)) {
+      $message = \Drupal::service('renderer')->render($message);
+    }
+
     $new = array(
       'safe' => SafeMarkup::isSafe($message),
       'message' => $message,
diff --git a/core/modules/system/src/Tests/Bootstrap/DrupalSetMessageTest.php b/core/modules/system/src/Tests/Bootstrap/DrupalSetMessageTest.php
index 37a1663..bf130b5 100644
--- a/core/modules/system/src/Tests/Bootstrap/DrupalSetMessageTest.php
+++ b/core/modules/system/src/Tests/Bootstrap/DrupalSetMessageTest.php
@@ -43,4 +43,12 @@ function testDuplicatedMessages() {
     $this->assertNoUniqueText('Duplicated message');
   }
 
+  /**
+   * Tests setting render array messages.
+   */
+  function testRenderArrayMessages() {
+    $this->drupalGet('system-test/drupal-set-message');
+    $this->assertText('Render array');
+  }
+
 }
diff --git a/core/modules/system/tests/modules/system_test/src/Controller/SystemTestController.php b/core/modules/system/tests/modules/system_test/src/Controller/SystemTestController.php
index 5ac7ca0..3b69300 100644
--- a/core/modules/system/tests/modules/system_test/src/Controller/SystemTestController.php
+++ b/core/modules/system/tests/modules/system_test/src/Controller/SystemTestController.php
@@ -103,6 +103,9 @@ public function drupalSetMessageTest() {
     drupal_set_message('First message (removed).');
     drupal_set_message('Second message (not removed).');
 
+    // Add a render array message.
+    drupal_set_message(['#markup' => 'Render array']);
+
     // Remove the first.
     unset($_SESSION['messages']['status'][0]);
 
@@ -112,6 +115,7 @@ public function drupalSetMessageTest() {
 
     drupal_set_message('Duplicated message', 'status', TRUE);
     drupal_set_message('Duplicated message', 'status', TRUE);
+
     return [];
   }