diff --git a/core/modules/datetime/datetime.module b/core/modules/datetime/datetime.module
index 3a016b5..40605ac 100644
--- a/core/modules/datetime/datetime.module
+++ b/core/modules/datetime/datetime.module
@@ -241,6 +241,11 @@ function template_preprocess_datetime_wrapper(&$variables) {
 
   if (!empty($element['#description'])) {
     $variables['description'] = $element['#description'];
+    // Add element class and id for screen readers.
+    $variables['attributes']['class'][] = 'description';
+    $variables['attributes']['id'] = $variables['attributes']['aria-describedby'];
+    // Remove aria-describedby attribute as it shouldn't be visible here.
+    unset($variables['attributes']['aria-describedby']);
   }
 
   $variables['content'] = $element['#children'];
@@ -384,6 +389,9 @@ function datetime_datetime_form_process($element, &$form_state) {
       $extra_attributes += array(
         'min' => $html5_min->format($date_format, $format_settings),
         'max' => $html5_max->format($date_format, $format_settings),
+        // Add the aria-describedby attribute to associate the form control with
+        // its description.
+        'aria-describedby' => $element['#id'] . '--description',
       );
     }
 
diff --git a/core/modules/datetime/templates/datetime-wrapper.html.twig b/core/modules/datetime/templates/datetime-wrapper.html.twig
index a4acf70..f4f8cfd 100644
--- a/core/modules/datetime/templates/datetime-wrapper.html.twig
+++ b/core/modules/datetime/templates/datetime-wrapper.html.twig
@@ -9,18 +9,21 @@
  * - attributes: HTML attributes for the form wrapper.
  * - required: (optional) A marker indicating that the form element is required.
  * - description: Description text for the form element.
+ * - attributes: HTML attributes for the containing element.
  *
  * @see template_preprocess_datetime_wrapper()
  *
  * @ingroup themeable
  */
 #}
-{% if title %}
-  <h4 class="label">
-    {% trans %}{{ title|passthrough }}{{ required|passthrough }}{% endtrans %}
-  </h4>
-{% endif %}
-{{ content }}
-{% if description %}
-  <div class="description">{{ description }}</div>
-{% endif %}
+<fieldset class="fieldgroup form-composite">
+  {% if title %}
+    <legend class="label">
+      {% trans %}{{ title|passthrough }}{{ required|passthrough }}{% endtrans %}
+    </legend>
+  {% endif %}
+  {{ content }}
+  {% if description %}
+      <div{{ attributes }}>{{ description }}</div>
+  {% endif %}
+</fieldset>