diff --git a/includes/common.inc b/includes/common.inc
index 0f7c014b5f..84998dfa04 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -5770,7 +5770,22 @@ function drupal_pre_render_conditional_comments($elements) {
 }
 
 /**
- * TODO
+ * Pre-render callback: Renders a generic HTML tag with attributes.
+ *
+ * @param array $elements
+ *   An associative array containing:
+ *   - #tag: The tag name to output. Typical tags added to the HTML HEAD:
+ *     - meta: To provide meta information, such as a page refresh.
+ *     - link: To refer to stylesheets and other contextual information.
+ *     - script: To load JavaScript.
+ *     The value of #tag is escaped.
+ *   - #attributes: (optional) An array of HTML attributes to apply to the
+ *     tag. The attributes are escaped, see \Drupal\Core\Template\Attribute.
+ *   - #value: (optional) A string containing tag content, such as inline
+ *     CSS. The value of #value will be XSS admin filtered if it is not safe.
+ *
+ * @return array
+ *   The render array.
  */
 function drupal_pre_render_htmltag(array $elements) {
   $void_elements = array(
@@ -5781,24 +5796,27 @@ function drupal_pre_render_htmltag(array $elements) {
 
   $attributes = isset($elements['#attributes']) ? drupal_attributes($elements['#attributes']) : '';
 
-  $open_tag = '<' . $elements['#tag'] . $attributes;
-  $close_tag = '</' . $elements['#tag'] . '>';
+  $tag = check_plain($elements['#tag']);
+
+  $open_tag = '<' . $tag . $attributes;
+  $close_tag = '</' . $tag . '>';
 
   // Construct a void element.
-  if (in_array($elements['#tag'], $void_elements, TRUE)) {
+  if (in_array($tag, $void_elements, TRUE)) {
     $open_tag .= ' />';
-    $close_tag = '';
+    $close_tag = "\n";
     $elements['#markup'] = NULL;
   } else {
     $open_tag .= '>';
+    $close_tag .= "\n";
     $elements['#markup'] = $elements['#value'];
   }
 
-  $open_tag .= $elements['#value_prefix'];
-  $close_tag = $elements['#value_suffix'] . $close_tag;
+  $elements['#markup'] = $elements['#value_prefix'] . $elements['#markup'];
+  $elements['#markup'] .= $elements['#value_suffix'];
 
   $elements['#prefix'] .= $open_tag;
-  $elements['#suffix'] = $close_tag . $elements['#suffix'] ."\n";
+  $elements['#suffix'] = $close_tag . $elements['#suffix'];
 
   $elements['#children'] = $elements['#markup'];
 
diff --git a/modules/simpletest/tests/theme.test b/modules/simpletest/tests/theme.test
index 3136b53452..5a043d59ee 100644
--- a/modules/simpletest/tests/theme.test
+++ b/modules/simpletest/tests/theme.test
@@ -546,44 +546,200 @@ class RenderElementTypesTestCase extends DrupalWebTestCase {
         ),
         'expected' => '<title>title test</title>' . "\n",
       ),
-      // Test html tag with nested elements.
       array(
-        'name' => "#type 'html_tag' with nested elements",
+        'name' => 'Value prefix/suffix.',
+        'value' => array(
+          '#type' => 'html_tag',
+          '#value' => 'value',
+          '#tag' => 'p',
+        ),
+        'expected' => '<p>value</p>' . "\n",
+      ),
+      array(
+        'name' => 'Normal element without a value should not result in a void element.',
+        'value' => array(
+          '#type' => 'html_tag',
+          '#value' => NULL,
+          '#tag' => 'p',
+        ),
+        'expected' => '<p></p>' . "\n",
+      ),
+      array(
+        'name' => 'A void element.',
+        'value' => array(
+          '#type' => 'html_tag',
+          '#tag' => 'br',
+        ),
+        'expected' => '<br />' . "\n",
+      ),
+      array(
+        'name' => 'Attributes.',
         'value' => array(
           '#type' => 'html_tag',
           '#tag' => 'div',
-          'child1' => array(
-            '#type' => 'html_tag',
-            '#tag' => 'em',
-            '#value' => 'test',
+          '#attributes' => array(
+            'class' => 'test',
+            'id' => 'id'
           ),
-          'child2' => array(
-            '#type' => 'html_tag',
-            '#tag' => 'span',
-            '#value' => 'value',
+          '#value' => 'value',
+        ),
+        'expected' => '<div class="test" id="id">value</div>' . "\n",
+      ),
+      array(
+        'name' => 'Ensure that #tag is sanitised.',
+        'value' => array(
+          '#type' => 'html_tag',
+          '#tag' => 'p><script>alert()</script><p',
+          '#value' => 'value',
+        ),
+        'expected' => '<p&gt;&lt;script&gt;alert()&lt;/script&gt;&lt;p>value</p&gt;&lt;script&gt;alert()&lt;/script&gt;&lt;p>' . "\n",
+      ),
+      array(
+        'name' => '',
+        'value' => array(
+          '#type' => 'html_tag',
+          '#tag' => 'p',
+          '#value' => '<script>value</script>',
+        ),
+        'expected' => '<p><script>value</script></p>' . "\n",
+      ),
+      array(
+        'name' => 'Ensure that nested render arrays render properly.',
+        'value' => array(
+          '#type' => 'html_tag',
+          '#tag' => 'p',
+          '#value' => NULL,
+          [
+            ['#markup' => '<b>value1</b>'],
+            ['#markup' => '<b>value2</b>'],
+          ],
+        ),
+        'expected' => '<p><b>value1</b><b>value2</b></p>' . "\n",
+      ),
+      array(
+        'name' => 'Ensure svg elements (rect)',
+        'value' =>  array(
+          '#type' => 'html_tag',
+          '#tag' => 'rect',
+          '#attributes' => array(
+            'width' => 25,
+            'height' => 25,
+            'x' => 5,
+            'y' => 10,
           ),
         ),
-        'expected' => '<div><em>test</em>' . "\n" . '<span>value</span>' . "\n" . '</div>' . "\n",
+        'expected' => '<rect width="25" height="25" x="5" y="10" />' . "\n",
       ),
-      // Test html tag with nested elements.
       array(
-        'name' => "#type 'html_tag' with nested elements",
+        'name' => 'Ensure svg elements (circle)',
+        'value' =>  array(
+          '#type' => 'html_tag',
+          '#tag' => 'circle',
+          '#attributes' => array(
+            'cx' => 100,
+            'cy' => 100,
+            'r' => 100,
+          ),
+        ),
+        'expected' => '<circle cx="100" cy="100" r="100" />' . "\n",
+      ),
+      array(
+        'name' => 'Ensure svg elements (polygon)',
+        'value' =>  array(
+          '#type' => 'html_tag',
+          '#tag' => 'polygon',
+          '#attributes' => array(
+            'points' => '60,20 100,40 100,80 60,100 20,80 20,40',
+          ),
+        ),
+        'expected' => '<polygon points="60,20 100,40 100,80 60,100 20,80 20,40" />' . "\n",
+      ),
+      array(
+        'name' => 'Ensure svg elements (use)',
+        'value' =>  array(
+          '#type' => 'html_tag',
+          '#tag' => 'use',
+          '#attributes' => array(
+            'x' => 50,
+            'y' => 10,
+            'width' => 50,
+            'height' => 50,
+          ),
+        ),
+        'expected' => '<use x="50" y="10" width="50" height="50" />' . "\n",
+      ),
+      array(
+        'name' => 'Ensure svg elements (path)',
+        'value' =>  array(
+          '#type' => 'html_tag',
+          '#tag' => 'path',
+          '#attributes' => array(
+            'd' => 'M 100 100 L 300 100 L 200 300 z',
+            'fill' => 'orange',
+            'stroke' => 'black',
+            'stroke-width' => 3,
+          ),
+        ),
+        'expected' => '<path d="M 100 100 L 300 100 L 200 300 z" fill="orange" stroke="black" stroke-width="3" />' . "\n",
+      ),
+      array(
+        'name' => 'Ensure svg elements (stop)',
+        'value' =>  array(
+          '#type' => 'html_tag',
+          '#tag' => 'stop',
+          '#attributes' => array(
+            'offset' => '5%',
+            'stop-color' => '#F60',
+          ),
+        ),
+        'expected' => '<stop offset="5%" stop-color="#F60" />' . "\n",
+      ),
+      array(
+        'name' => 'Ensure svg elements (linearGradient)',
         'value' => array(
           '#type' => 'html_tag',
-          '#tag' => 'div',
-          '#value' => 'title test',
-          'child1' => array(
+          '#tag' => 'linearGradient',
+          '#value' => NULL,
+          array(
             '#type' => 'html_tag',
-            '#tag' => 'em',
-            '#value' => 'test',
+            '#tag' => 'stop',
+            '#value' => NULL,
+            '#attributes' => array(
+              'offset' => '5%',
+              'stop-color' => '#F60',
+            ),
           ),
-          'child2' => array(
+          array(
             '#type' => 'html_tag',
-            '#tag' => 'span',
-            '#value' => 'value',
+            '#tag' => 'stop',
+            '#value' => NULL,
+            '#attributes' => array(
+              'offset' => '95%',
+              'stop-color' => '#FF6',
+            ),
+          ),
+        ),
+        'expected' => '<linearGradient><stop offset="5%" stop-color="#F60" />' . "\n" . '<stop offset="95%" stop-color="#FF6" />' . "\n" . '</linearGradient>' . "\n",
+      ),
+      array(
+        'name' => 'Simple link.',
+        'value' => array(
+          '#type' => 'html_tag',
+          '#tag' => 'link',
+        ),
+        'expected' => '<link />' . "\n",
+      ),
+      array(
+        'name' => 'Conditional link.',
+        'value' => array(
+          '#type' => 'html_tag',
+          '#tag' => 'link',
+          '#browsers' => array(
+            'IE' => TRUE,
+            '!IE' => FALSE,
           ),
         ),
-        'expected' => '<div>title test</div>' . "\n",
+        'expected' => "\n" . '<!--[if IE]>' . "\n" . '<link />' . "\n" . '<![endif]-->' . "\n",
       ),
     );