core/modules/big_pipe/big_pipe.services.yml  |  2 +-
 core/modules/big_pipe/src/Render/BigPipe.php | 92 ++++++++++++++++++----------
 2 files changed, 59 insertions(+), 35 deletions(-)

diff --git a/core/modules/big_pipe/big_pipe.services.yml b/core/modules/big_pipe/big_pipe.services.yml
index 32008fd..d47a39e 100644
--- a/core/modules/big_pipe/big_pipe.services.yml
+++ b/core/modules/big_pipe/big_pipe.services.yml
@@ -11,4 +11,4 @@ services:
     arguments: ['@current_user']
   big_pipe:
     class: Drupal\big_pipe\Render\BigPipe
-    arguments: ['@renderer', '@session', '@ajax_response.attachments_processor', '@html_response.attachments_processor']
+    arguments: ['@renderer', '@session', '@request_stack', '@http_kernel', '@event_dispatcher']
diff --git a/core/modules/big_pipe/src/Render/BigPipe.php b/core/modules/big_pipe/src/Render/BigPipe.php
index b85e625..a053f9c 100644
--- a/core/modules/big_pipe/src/Render/BigPipe.php
+++ b/core/modules/big_pipe/src/Render/BigPipe.php
@@ -14,7 +14,9 @@
 use Drupal\Core\Render\RendererInterface;
 use Drupal\Core\Render\AttachmentsResponseProcessorInterface;
 use Symfony\Component\EventDispatcher\EventDispatcher;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\RequestStack;
 use Symfony\Component\HttpFoundation\Session\SessionInterface;
 use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
@@ -42,18 +44,25 @@ class BigPipe implements BigPipeInterface {
   protected $session;
 
   /**
-   * The AJAX response attachments processor service.
+   * The request stack.
    *
-   * @var \Drupal\Core\Render\AttachmentsResponseProcessorInterface
+   * @var \Symfony\Component\HttpFoundation\RequestStack
    */
-  protected $ajaxResponseAttachmentsProcessor;
+  protected $requestStack;
 
   /**
-   * The HTML response attachments processor service.
+   * The HTTP kernel.
    *
-   * @var \Drupal\Core\Render\AttachmentsResponseProcessorInterface
+   * @var \Symfony\Component\HttpKernel\HttpKernelInterface
    */
-  protected $htmlResponseAttachmentsProcessor;
+  protected $httpKernel;
+
+  /**
+   * The event dispatcher.
+   *
+   * @var \Symfony\Component\EventDispatcher\EventDispatcherInterface
+   */
+  protected $eventDispatcher;
 
   /**
    * Constructs a new BigPipe class.
@@ -62,16 +71,19 @@ class BigPipe implements BigPipeInterface {
    *   The renderer.
    * @param \Symfony\Component\HttpFoundation\Session\SessionInterface $session
    *   The session.
-   * @param \Drupal\Core\Render\AttachmentsResponseProcessorInterface $ajax_response_attachments_processor
-   *   The AJAX response attachments processor service.
-   * @param \Drupal\Core\Render\AttachmentsResponseProcessorInterface $html_response_attachments_processor
-   *   The HTML response attachments processor service.
+   * @param \Symfony\Component\HttpFoundation\RequestStack
+   *   The request stack.
+   * @param \Symfony\Component\HttpKernel\HttpKernelInterface
+   *   The HTTP kernel.
+   * @param \Symfony\Component\EventDispatcher\EventDispatcherInterface $event_dispatcher
+   *   The event dispatcher.
    */
-  public function __construct(RendererInterface $renderer, SessionInterface $session, AttachmentsResponseProcessorInterface $ajax_response_attachments_processor, AttachmentsResponseProcessorInterface $html_response_attachments_processor) {
+  public function __construct(RendererInterface $renderer, SessionInterface $session, RequestStack $request_stack, HttpKernelInterface $http_kernel, EventDispatcherInterface $event_dispatcher) {
     $this->renderer = $renderer;
     $this->session = $session;
-    $this->ajaxResponseAttachmentsProcessor = $ajax_response_attachments_processor;
-    $this->htmlResponseAttachmentsProcessor= $html_response_attachments_processor;
+    $this->requestStack = $request_stack;
+    $this->httpKernel = $http_kernel;
+    $this->eventDispatcher = $event_dispatcher;
   }
 
   /**
@@ -163,6 +175,16 @@ public function sendContent($content, $attachments, array $placeholders) {
     // Sort placeholders by the order in which they appear in the markup.
     $order = $this->getPlaceholderOrder($content);
 
+    // A BigPipe response consists of a HTML response plus multiple embedded
+    // AJAX responses. To process the attachments of those AJAX responses, we
+    // need a fake request that is identical to the master request, but with
+    // one change: it must have the right Accept header, otherwise the work-
+    // around for a bug in IE9 will cause not JSON, but <textarea>-wrapped JSON
+    // to be returned.
+    // @see \Drupal\Core\EventSubscriber\AjaxResponseSubscriber::onResponse()
+    $fake_request = $this->requestStack->getMasterRequest()->duplicate();
+    $fake_request->headers->set('Accept', 'application/json');
+
     foreach ($order as $placeholder) {
       if (!isset($placeholders[$placeholder])) {
         continue;
@@ -179,25 +201,28 @@ public function sendContent($content, $attachments, array $placeholders) {
       $elements = $this->renderPlaceholder($placeholder, $placeholder_elements);
 
       // Create a new AjaxResponse.
-      $response = new AjaxResponse();
-      $response->addCommand(new ReplaceCommand(sprintf('[data-big-pipe-selector="%s"]', $placeholder), $elements['#markup']));
-      $response->setAttachments($elements['#attached']);
-
-      // @todo Clean up.
-      $request_stack = \Drupal::service('request_stack');
-      $master_request = $request_stack->getMasterRequest();
-      $request = Request::create($master_request->getUri(), $master_request->getMethod(), $master_request->query->all(), $master_request->cookies->all(), array(), $master_request->server->all());
-      $request->headers->set('Accept', 'application/json');
-      $request->request->set('ajax_page_state', ['libraries' => implode(',', $assets->getAlreadyLoadedLibraries())] + $assets->getSettings()['ajaxPageState']);
-      $request_stack->push($request);
-      $event = new FilterResponseEvent(\Drupal::service('http_kernel.basic'), $request, HttpKernelInterface::SUB_REQUEST, $response);
-      \Drupal::service('event_dispatcher')->dispatch(KernelEvents::RESPONSE, $event);
-      $response = $event->getResponse();
-      $request_stack->pop();
-
-      // @todo Filter response.
-      $json = $response->getContent();
-
+      $ajax_response = new AjaxResponse();
+      $ajax_response->addCommand(new ReplaceCommand(sprintf('[data-big-pipe-selector="%s"]', $placeholder), $elements['#markup']));
+      $ajax_response->setAttachments($elements['#attached']);
+
+      // Push a fake request with the asset libraries loaded so far and dispatch
+      // KernelEvents::RESPONSE event. This results in the attachments for the
+      // AJAX response being processed by AjaxResponseAttachmentsProcessor and
+      // hence:
+      // - the necessary AJAX commands to load the necessary missing asset
+      //   libraries and updated AJAX page state are added to the AJAX response
+      // - the attachments associated with the response are finalized, which
+      //   allows us to track the total set of asset libraries sent in the
+      //   initial HTML response plus all embedded AJAX responses sent so far.
+      $fake_request->request->set('ajax_page_state', ['libraries' => implode(',', $assets->getAlreadyLoadedLibraries())] + $assets->getSettings()['ajaxPageState']);
+      $this->requestStack->push($fake_request);
+      $event = new FilterResponseEvent($this->httpKernel, $fake_request, HttpKernelInterface::SUB_REQUEST, $ajax_response);
+      $this->eventDispatcher->dispatch(KernelEvents::RESPONSE, $event);
+      $ajax_response = $event->getResponse();
+      $this->requestStack->pop();
+
+      // Send this embedded AJAX response.
+      $json = $ajax_response->getContent();
       $output = <<<EOF
     <script type="application/json" data-big-pipe-placeholder="$placeholder" data-drupal-ajax-processor="big_pipe">
     $json
@@ -205,12 +230,11 @@ public function sendContent($content, $attachments, array $placeholders) {
 
 EOF;
       print $output;
-
       flush();
 
       // Another placeholder was rendered and sent, track the set of asset
       // libraries sent so far.
-      $assets->setAlreadyLoadedLibraries(explode(',', $response->getAttachments()['drupalSettings']['ajaxPageState']['libraries']));
+      $assets->setAlreadyLoadedLibraries(explode(',', $ajax_response->getAttachments()['drupalSettings']['ajaxPageState']['libraries']));
     }
 
     // Send the stop signal.