diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/Taxonomy.php b/core/modules/taxonomy/lib/Drupal/taxonomy/Taxonomy.php
index 5ee7d89..345ad3e 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/Taxonomy.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/Taxonomy.php
@@ -55,20 +55,12 @@ public function setContainer(ContainerInterface $container = NULL) {
    *
    * @param string $field_name
    *   The name of the term reference field.
-   * @param string $tags_typed
-   *   (optional) A comma-separated list of term names entered in the
-   *   autocomplete form element. Only the last term is used for autocompletion.
-   *   Defaults to '' (an empty string).
    *
    * @see taxonomy_menu()
    * @see taxonomy_field_widget_info()
    */
-  public function autocomplete($field_name, $tags_typed = '') {
-    $args = arg();
-    unset($args[0]);
-    unset($args[1]);
-    unset($args[2]);
-    $tags_typed = implode('/', $args);
+  public function autocomplete($field_name) {
+    $tags_typed = drupal_container()->get('request')->query->get('q');
 
     // Make sure the field exists and is a taxonomy field.
     if (!($field = field_info_field($field_name)) || $field['type'] !== 'taxonomy_term_reference') {
diff --git a/core/modules/taxonomy/taxonomy.routing.yml b/core/modules/taxonomy/taxonomy.routing.yml
index 35c66fc..5cca0f5 100644
--- a/core/modules/taxonomy/taxonomy.routing.yml
+++ b/core/modules/taxonomy/taxonomy.routing.yml
@@ -1,7 +1,6 @@
 taxonomy_autocomplete:
-  pattern: '/taxonomy/autocomplete/{field_name}/{tags_typed}'
+  pattern: '/taxonomy/autocomplete/{field_name}'
   defaults:
     _controller: '\Drupal\taxonomy\TaxonomyRouteController::autocomplete'
   requirements:
     _permission: 'access content'
-