diff --git a/core/modules/file/file.js b/core/modules/file/file.js
index 8ed377e..bfdb85e 100644
--- a/core/modules/file/file.js
+++ b/core/modules/file/file.js
@@ -7,7 +7,7 @@
  * prevents separate file fields from accidentally uploading files).
  */
 
-(function ($, Drupal) {
+(function ($, Drupal, debounce) {
 
   'use strict';
 
@@ -88,13 +88,15 @@
   Drupal.behaviors.fileButtons = {
     attach: function (context) {
       var $context = $(context);
-      $context.find('.js-form-submit').on('mousedown', Drupal.file.disableFields);
-      $context.find('.js-form-managed-file .js-form-submit').on('mousedown', Drupal.file.progressBar);
+      var $submit = $context.find('.js-form-submit');
+      $submit.on('mousedown.fileButtons', Drupal.fileHandlerDebounce.disableFields);
+      var $managedFileSubmit = $context.find('.js-form-managed-file .js-form-submit');
+      $managedFileSubmit.on('mousedown.fileButtons', Drupal.fileHandlerDebounce.progressBar);
     },
     detach: function (context) {
       var $context = $(context);
-      $context.find('.js-form-submit').off('mousedown', Drupal.file.disableFields);
-      $context.find('.js-form-managed-file .js-form-submit').off('mousedown', Drupal.file.progressBar);
+      $context.find('.js-form-submit').off('mousedown.fileButtons');
+      $context.find('.js-form-managed-file .js-form-submit').off('mousedown.fileButtons');
     }
   };
 
@@ -170,7 +172,14 @@
      *   The event triggered. For example `change.autoFileUpload`.
      */
     triggerUploadButton: function (event) {
-      $(event.target).closest('.js-form-managed-file').find('.js-form-submit').trigger('mousedown');
+      var $submit = $(event.target).closest('.js-form-managed-file').find('.js-form-submit');
+      if ($submit.length) {
+        // Calling event handlers immediately.
+        Drupal.fileHandlerDebounce.disableFields.apply($submit[0], [event]);
+        Drupal.fileHandlerDebounce.progressBar.apply($submit[0], [event]);
+        // Triggering mousedown on submit button may start an asynchronous upload thread.
+      }
+      $submit.trigger('mousedown');
     },
 
     /**
@@ -254,4 +263,30 @@
     }
   };
 
-})(jQuery, Drupal);
+  /**
+   * Helper class to debounde event handlers in Drupal.file.
+   */
+  Drupal.fileHandlerDebounce = Drupal.fileHandlerDebounce || {
+
+    /**
+     * Debounced version of Drupal.file.disableFields().
+     *
+     * @name Drupal.fileHandlerDebounce.disableFields
+     *
+     * @param {jQuery.Event} event
+     *   The event triggered, most likely a `mousedown` event.
+     */
+    disableFields: debounce(Drupal.file.disableFields, 100, true),
+
+    /**
+     * Debounced version of Drupal.file.progressBar().
+     *
+     * @name Drupal.fileHandlerDebounce.progressBar
+     *
+     * @param {jQuery.Event} event
+     *   The event triggered, most likely a `mousedown` event.
+     */
+    progressBar: debounce(Drupal.file.progressBar, 100, true)
+  };
+
+})(jQuery, Drupal, Drupal.debounce);
diff --git a/core/modules/file/file.libraries.yml b/core/modules/file/file.libraries.yml
index ccc0c3b..659de14 100644
--- a/core/modules/file/file.libraries.yml
+++ b/core/modules/file/file.libraries.yml
@@ -10,3 +10,4 @@
     - core/jquery.once
     - core/drupal
     - core/drupalSettings
+    - core/drupal.debounce