diff --git a/core/lib/Drupal/Component/Utility/Xss.php b/core/lib/Drupal/Component/Utility/Xss.php
index ddce1799b462d0bd3f1c733cc13cae608146d5b4..7a771822aa3ae4a2ecdffb2dbb03b11b387f49e8 100644
--- a/core/lib/Drupal/Component/Utility/Xss.php
+++ b/core/lib/Drupal/Component/Utility/Xss.php
@@ -152,7 +152,7 @@ protected static function split($string, $html_tags, $split_mode) {
       return '<';
     }
 
-    if (!preg_match('%^<\s*(/\s*)?([a-zA-Z0-9]+)([^>]*)>?|(<!--.*?-->)$%', $string, $matches)) {
+    if (!preg_match('%^<\s*(/\s*)?([a-zA-Z0-9\-]+)([^>]*)>?|(<!--.*?-->)$%', $string, $matches)) {
       // Seriously malformed.
       return '';
     }
diff --git a/core/tests/Drupal/Tests/Component/Utility/XssTest.php b/core/tests/Drupal/Tests/Component/Utility/XssTest.php
index a682fb1cc094f3cbf2ee2cf4943e73a4ea423de0..7f45b17323d88cd73f4e984b6dbe6606a1f8f00a 100644
--- a/core/tests/Drupal/Tests/Component/Utility/XssTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/XssTest.php
@@ -59,11 +59,19 @@ protected function setUp() {
    *   The expected result.
    * @param string $message
    *   The assertion message to display upon failure.
+   * @param array $allowed_tags
+   *   (optional) The allowed HTML tags to be passed to \Drupal\Component\Utility\Xss::filter().
    *
    * @dataProvider providerTestFilterXssNormalized
    */
-  public function testFilterXssNormalized($value, $expected, $message) {
-    $this->assertNormalized(Xss::filter($value), $expected, $message);
+  public function testFilterXssNormalized($value, $expected, $message, array $allowed_tags = NULL) {
+    if ($allowed_tags === NULL) {
+      $value = Xss::filter($value);
+    }
+    else {
+      $value = Xss::filter($value, $allowed_tags);
+    }
+    $this->assertNormalized($value, $expected, $message);
   }
 
   /**
@@ -76,6 +84,8 @@ public function testFilterXssNormalized($value, $expected, $message) {
    *     - The value to filter.
    *     - The value to expect after filtering.
    *     - The assertion message.
+   *     - (optional) The allowed HTML HTML tags array that should be passed to
+   *       \Drupal\Component\Utility\Xss::filter().
    */
   public function providerTestFilterXssNormalized() {
     return array(
@@ -94,6 +104,13 @@ public function providerTestFilterXssNormalized() {
         "who&amp;#039; online",
         'HTML filter -- double encoded html entity number',
       ),
+      // Custom elements with dashes in the tag name.
+      array(
+        "<test-element></test-element>",
+        "<test-element></test-element>",
+        'Custom element with dashes in tag name.',
+        array('test-element'),
+      ),
     );
   }