diff --git a/core/includes/common.inc b/core/includes/common.inc
index 19beefa..63372e3 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -630,7 +630,8 @@ function drupal_merge_attached(array $a, array $b) {
  */
 function drupal_process_attached(array $elements) {
   // Asset attachments are handled by \Drupal\Core\Asset\AssetResolver.
-  foreach (array('library', 'drupalSettings') as $type) {
+  // @todo This needs to be configurable somehow.
+  foreach (array('library', 'drupalSettings', 'big_pipe_placeholders') as $type) {
     unset($elements['#attached'][$type]);
   }
 
diff --git a/core/lib/Drupal/Core/Render/Renderer.php b/core/lib/Drupal/Core/Render/Renderer.php
index bb8f1ff..7870042 100644
--- a/core/lib/Drupal/Core/Render/Renderer.php
+++ b/core/lib/Drupal/Core/Render/Renderer.php
@@ -167,7 +167,7 @@ public function renderPlain(&$elements) {
    *
    * @todo Make public as part of https://www.drupal.org/node/2469431
    */
-  protected function renderPlaceholder($placeholder, array $elements) {
+  public function renderPlaceholder($placeholder, array $elements) {
     // Get the render array for the given placeholder
     $placeholder_elements = $elements['#attached']['placeholders'][$placeholder];
 
diff --git a/core/modules/big_pipe/big_pipe.info.yml b/core/modules/big_pipe/big_pipe.info.yml
new file mode 100644
index 0000000..b0f6e91
--- /dev/null
+++ b/core/modules/big_pipe/big_pipe.info.yml
@@ -0,0 +1,6 @@
+name: BigPipe
+type: module
+description: 'Enables BigPipe for authenticated users; first send+render the cheap parts of the page, then the expensive parts.'
+package: Core
+version: VERSION
+core: 8.x
diff --git a/core/modules/big_pipe/big_pipe.libraries.yml b/core/modules/big_pipe/big_pipe.libraries.yml
new file mode 100644
index 0000000..88ecff6
--- /dev/null
+++ b/core/modules/big_pipe/big_pipe.libraries.yml
@@ -0,0 +1,11 @@
+big_pipe:
+  version: VERSION
+  js:
+    js/big_pipe.js: {}
+  drupalSettings:
+    bigPipePlaceholders: []
+  dependencies:
+    - core/jquery
+    - core/drupal
+    - core/drupal.ajax
+    - core/drupalSettings
diff --git a/core/modules/big_pipe/big_pipe.module b/core/modules/big_pipe/big_pipe.module
new file mode 100644
index 0000000..3bb6aca
--- /dev/null
+++ b/core/modules/big_pipe/big_pipe.module
@@ -0,0 +1,56 @@
+<?php
+
+/**
+ * @file
+ * Enables BigPipe for authenticated users; first send+render the cheap parts
+ * of the page, then the expensive parts.
+ *
+ * BigPipe allows to send a page in chunks. First the main content is sent and
+ * then uncacheable data that takes long to generate.
+ */
+
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Render\SafeString;
+
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function big_pipe_form_user_login_form_alter(&$form, FormStateInterface $form_state, $form_id) {
+  // Check if the user has JavaScript enabled without adding JavaScript.
+  $form['big_pipe_has_js'] = array(
+    '#type' => 'hidden',
+    '#default_value' => '1',
+  );
+
+  $form['#after_build'][] = 'big_pipe_form_after_build';
+  $form['#submit'][] = 'big_pipe_form_set_js_check';
+}
+
+/**
+ * After build handler for user_login_form().
+ */
+function big_pipe_form_after_build($form, FormStateInterface $form_state) {
+  // This is tricky: We want Form API to default big_pipe_has_js to 1 in
+  // case it gets not send. We also want to set the value of the HTML element
+  // to 0 and add <noscript> tags.
+  // So in case the user has JS disabled, the noscript is parsed and
+  // big_pipe_has_js is send with '0', else it is not send at all and FAPI falls
+  // back to the default value, which is '1'.
+  $form['big_pipe_has_js']['#value'] = '0';
+  $form['big_pipe_has_js']['#prefix'] = SafeString::create('<noscript>');
+  $form['big_pipe_has_js']['#suffix'] = SafeString::create('</noscript>');
+  return $form;
+}
+
+/**
+ * Form submission handler for user_login_form().
+ *
+ * Store if the user has javascript available in the SESSION.
+ */
+function big_pipe_form_set_js_check($form, FormStateInterface $form_state) {
+  $current_user = \Drupal::currentUser();
+
+  if ($current_user->isAuthenticated()) {
+    $_SESSION['big_pipe_has_js'] = $form_state->getValue('big_pipe_has_js') == 1;
+  }
+}
diff --git a/core/modules/big_pipe/big_pipe.permissions.yml b/core/modules/big_pipe/big_pipe.permissions.yml
new file mode 100644
index 0000000..db506e0
--- /dev/null
+++ b/core/modules/big_pipe/big_pipe.permissions.yml
@@ -0,0 +1,2 @@
+Use BigPipe placeholder strategy:
+  title: 'Use the BigPipe placeholder strategy'
diff --git a/core/modules/big_pipe/big_pipe.services.yml b/core/modules/big_pipe/big_pipe.services.yml
new file mode 100644
index 0000000..0218138
--- /dev/null
+++ b/core/modules/big_pipe/big_pipe.services.yml
@@ -0,0 +1,14 @@
+services:
+  html_response.big_pipe_subscriber:
+    class: Drupal\big_pipe\EventSubscriber\HtmlResponseBigPipeSubscriber
+    tags:
+      - { name: event_subscriber }
+    arguments: ['@big_pipe']
+  placeholder_strategy.big_pipe:
+    class: Drupal\big_pipe\Render\Placeholder\BigPipeStrategy
+    tags:
+      - { name: placeholder_strategy, priority: 0 }
+    arguments: ['@current_user']
+  big_pipe:
+    class: Drupal\big_pipe\Render\BigPipe
+    arguments: ['@renderer', '@ajax_response.attachments_processor']
diff --git a/core/modules/big_pipe/js/big_pipe.js b/core/modules/big_pipe/js/big_pipe.js
new file mode 100644
index 0000000..489a5f5
--- /dev/null
+++ b/core/modules/big_pipe/js/big_pipe.js
@@ -0,0 +1,90 @@
+/**
+ * @file
+ * Provides Ajax page updating via BigPipe.
+ */
+
+(function ($, window, Drupal, drupalSettings) {
+
+  "use strict";
+
+  var interval = 100; // Check every 100 ms.
+  var maxWait = 10; // Wait for a maximum of 10 seconds.
+
+  // The internal ID to contain the watcher service.
+  var intervalID;
+
+  function BigPipeClearInterval() {
+    if (intervalID) {
+      clearInterval(intervalID);
+      intervalID = undefined;
+    }
+  }
+
+  function BigPipeProcessPlaceholders(context) {
+    var $container = jQuery('[data-big-pipe-container=1]', context);
+
+    if (!$container.length) {
+      return;
+    }
+
+    // Process BigPipe inlined ajax responses.
+    $container.find('script[data-drupal-ajax-processor="big_pipe"]').each(function() {
+      var placeholder = $(this).data('big-pipe-placeholder');
+
+      // Ignore any placeholders that are not in the known placeholder list.
+      // This is used to avoid someone trying to XSS the site via the
+      // placeholdering mechanism.
+      if (typeof(drupalSettings.bigPipePlaceholders[placeholder]) !== 'undefined') {
+        var response = JSON.parse(this.textContent);
+        // Use a dummy url.
+        var ajaxObject = Drupal.ajax({url: 'big-pipe/placeholder.json'});
+        ajaxObject.success(response);
+      }
+      $(this).remove();
+    });
+
+    // Check for start signal to attachBehaviors.
+    $container.find('script[data-big-pipe-start="1"]').each(function() {
+      $(this).remove();
+      Drupal.attachBehaviors();
+    });
+
+    // Check for stop signal to stop checking.
+    $container.find('script[data-big-pipe-stop="1"]').each(function() {
+      $(this).remove();
+      BigPipeClearInterval();
+    });
+  }
+
+  $('body').each(function() {
+    if ($(this).data('big-pipe-processed') == true) {
+      return;
+    }
+
+    $(this).data('big-pipe-processed', true);
+
+    // Check for new BigPipe elements until we get the stop signal or the timeout occurs.
+    intervalID = setInterval(function() {
+      BigPipeProcessPlaceholders(document);
+    }, 100);
+
+    // Wait for a maxium of maxWait seconds.
+    setTimeout(BigPipeClearInterval, maxWait * 1000);
+  });
+
+  /**
+   * Defines the BigPipe behavior.
+   *
+   * @type {Drupal~behavior}
+   */
+  Drupal.behaviors.BigPipe = {
+    attach: function (context, settings) {
+      if (!intervalID) {
+        // If we timeout before all data is loaded, try again once
+        // the regular ready() event fires.
+        BigPipeProcessPlaceholders(context);
+      }
+    }
+  };
+
+})(jQuery, this, Drupal, drupalSettings);
diff --git a/core/modules/big_pipe/src/EventSubscriber/HtmlResponseBigPipeSubscriber.php b/core/modules/big_pipe/src/EventSubscriber/HtmlResponseBigPipeSubscriber.php
new file mode 100644
index 0000000..c9a3f44
--- /dev/null
+++ b/core/modules/big_pipe/src/EventSubscriber/HtmlResponseBigPipeSubscriber.php
@@ -0,0 +1,90 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\big_pipe\EventSubscriber\HtmlResponseBigPipeSubscriber.
+ */
+
+namespace Drupal\big_pipe\EventSubscriber;
+
+use Drupal\Core\Render\HtmlResponse;
+use Drupal\big_pipe\Render\BigPipeInterface;
+use Drupal\big_pipe\Render\BigPipeResponse;
+use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
+use Symfony\Component\HttpKernel\KernelEvents;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * HTML response subscriber to replace the Response with a BigPipe Response.
+ */
+class HtmlResponseBigPipeSubscriber implements EventSubscriberInterface {
+
+  /**
+   * The BigPipe service.
+   *
+   * @var \Drupal\big_pipe\Render\BigPipeInterface
+   */
+  protected $bigPipe;
+
+  /**
+   * Constructs a HtmlResponseBigPipeSubscriber object.
+   *
+   * @param \Drupal\big_pipe\Render\BigPipeInterface $big_pipe
+   *   The BigPipe service.
+   */
+  public function __construct(BigPipeInterface $big_pipe) {
+    $this->bigPipe = $big_pipe;
+  }
+
+  /**
+   * Processes placeholders for HTML responses.
+   *
+   * @param \Symfony\Component\HttpKernel\Event\FilterResponseEvent $event
+   *   The event to process.
+   */
+  public function onRespond(FilterResponseEvent $event) {
+    if (!$event->isMasterRequest()) {
+      return;
+    }
+
+    $response = $event->getResponse();
+    if (!$response instanceof HtmlResponse) {
+      return;
+    }
+
+    $attachments = $response->getAttachments();
+    if (empty($attachments['big_pipe_placeholders'])) {
+      return;
+    }
+
+    // Create a new Response.
+    $big_pipe_response = new BigPipeResponse();
+
+    // Clone the response.
+    $big_pipe_response->headers = clone $response->headers;
+    $big_pipe_response->setStatusCode($response->getStatusCode());
+    $big_pipe_response->setContent($response->getContent());
+    $big_pipe_response->addCacheableDependency($response->getCacheableMetadata());
+
+    // Inject the placeholders and service into the response.
+    $big_pipe_response->setBigPipePlaceholders($attachments['big_pipe_placeholders']);
+    $big_pipe_response->setBigPipeService($this->bigPipe);
+    unset($attachments['big_pipe_placeholders']);
+
+    // Set the remaining attachments.
+    $big_pipe_response->setAttachments($attachments);
+
+    // And set the new response.
+    $event->setResponse($big_pipe_response);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    // Run as pretty much last subscriber.
+    $events[KernelEvents::RESPONSE][] = ['onRespond', -10000];
+    return $events;
+  }
+
+}
diff --git a/core/modules/big_pipe/src/Render/BigPipe.php b/core/modules/big_pipe/src/Render/BigPipe.php
new file mode 100644
index 0000000..7261d6d
--- /dev/null
+++ b/core/modules/big_pipe/src/Render/BigPipe.php
@@ -0,0 +1,126 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\big_pipe\Render\BigPipe.
+ */
+
+namespace Drupal\big_pipe\Render;
+
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\ReplaceCommand;
+use Drupal\Core\Render\RendererInterface;
+use Drupal\Core\Render\AttachmentsResponseProcessorInterface;
+
+/**
+ * A class that allows sending the main content first, then replace
+ * placeholders to send the rest using Javascript replacements.
+ */
+class BigPipe implements BigPipeInterface {
+
+  /**
+   * The renderer.
+   *
+   * @var \Drupal\Core\Render\RendererInterface
+   */
+  protected $renderer;
+
+  /**
+   * The AJAX response attachments processor service.
+   *
+   * @var \Drupal\Core\Render\AttachmentsResponseProcessorInterface
+   */
+  protected $ajaxResponseAttachmentsProcessor;
+
+  /**
+   * Constructs a new BigPipe class.
+   *
+   * @param \Drupal\Core\Render\RendererInterface
+   *   The renderer.
+   * @param \Drupal\Core\Render\AttachmentsResponseProcessorInterface $ajax_response_attachments_processor
+   *   The AJAX response attachments processor service.
+   */
+  public function __construct(RendererInterface $renderer, AttachmentsResponseProcessorInterface $ajax_response_attachments_processor) {
+    $this->renderer = $renderer;
+    $this->ajaxResponseAttachmentsProcessor = $ajax_response_attachments_processor;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function sendContent($content, array $placeholders) {
+    // Split it up in various chunks.
+    $split = '<!-- X-RENDER-CACHE-BIG-PIPE-SPLIT -->';
+    if (strpos($content, $split) === FALSE) {
+      $split = '</body>';
+    }
+    $page_parts = explode($split, $content);
+
+    if (count($page_parts) !== 2) {
+      throw new \LogicException("You need to have only one body or one <!-- X-RENDER-CACHE-BIG-PIPE-SPLIT --> tag in your html.html.twig template file.");
+    }
+
+    // Support streaming on NGINX + php-fpm (nginx >= 1.5.6).
+    header('X-Accel-Buffering: no');
+
+    print $page_parts[0];
+
+    // Print a container and the start signal.
+    print "\n";
+    print '  <div data-big-pipe-container="1">' . "\n";
+    print '    <script type="application/json" data-big-pipe-start="1"></script>' . "\n";
+
+    ob_end_flush();
+    flush();
+
+    ksort($placeholders);
+
+    foreach ($placeholders as $placeholder => $placeholder_elements) {
+      // Check if the placeholder is present at all.
+      if (strpos($content, $placeholder) === FALSE) {
+        continue;
+      }
+
+      // Create elements to process in right format.
+      $elements = [
+        '#markup' => $placeholder,
+        '#attached' => [
+          'placeholders' => [
+            $placeholder => $placeholder_elements,
+          ],
+        ],
+      ];
+
+      $elements = $this->renderer->renderPlaceholder($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']);
+
+      $this->ajaxResponseAttachmentsProcessor->processAttachments($response);
+
+      // @todo Filter response.
+      $json = $response->getContent();
+
+      $output = <<<EOF
+    <script type="application/json" data-big-pipe-placeholder="$placeholder" data-drupal-ajax-processor="big_pipe">
+    $json
+    </script>
+
+EOF;
+      print $output;
+
+      flush();
+    }
+
+    // Send the stop signal.
+    print '    <script type="application/json" data-big-pipe-stop="1"></script>' . "\n";
+    print '  </div>' . "\n";
+
+    print $split;
+    print $page_parts[1];
+
+    return $this;
+  }
+}
diff --git a/core/modules/big_pipe/src/Render/BigPipeInterface.php b/core/modules/big_pipe/src/Render/BigPipeInterface.php
new file mode 100644
index 0000000..221791d
--- /dev/null
+++ b/core/modules/big_pipe/src/Render/BigPipeInterface.php
@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\big_pipe\Render\BigPipeInterface.
+ */
+
+namespace Drupal\big_pipe\Render;
+
+/**
+ * An interface that allows sending the main content first, then replace
+ * placeholders to send the rest using Javascript replacements.
+ */
+interface BigPipeInterface {
+
+  /**
+   * Sends the content to the browser, splitting before the closing </body> tag
+   * and afterwards processes placeholders to send when they have been rendered.
+   *
+   * The output buffers are flushed in between.
+   *
+   * @param array $placeholders
+   *   The placeholders to process.
+   * @param string $content
+   *   The content to send.
+   */
+  public function sendContent($content, array $placeholders);
+
+}
diff --git a/core/modules/big_pipe/src/Render/BigPipeResponse.php b/core/modules/big_pipe/src/Render/BigPipeResponse.php
new file mode 100644
index 0000000..168b0d1
--- /dev/null
+++ b/core/modules/big_pipe/src/Render/BigPipeResponse.php
@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\big_pipe\Render\BigPipeResponse.
+ */
+
+namespace Drupal\big_pipe\Render;
+
+use Drupal\Core\Render\HtmlResponse;
+
+/**
+ * A response that allows to send placeholders after the main content has been
+ * send.
+ */
+class BigPipeResponse extends HtmlResponse {
+
+  /**
+   * An array of placeholders to process.
+   *
+   * @var array
+   */
+  protected $bigPipePlaceholders;
+
+  /**
+   * The BigPipe service.
+   *
+   * @var \Drupal\big_pipe\Render\BigPipeInterface
+   */
+  protected $bigPipe;
+
+  /**
+   * Sets the big pipe placeholders to process.
+   *
+   * @param array $placeholders
+   *   The placeholders to process.
+   */
+  public function setBigPipePlaceholders(array $placeholders) {
+    $this->bigPipePlaceholders = $placeholders;
+  }
+
+  /**
+   * Sets the big pipe service to use.
+   *
+   * @param \Drupal\big_pipe\Render\BigPipeInterface $big_pipe
+   *   The BigPipe service.
+   */
+  public function setBigPipeService(BigPipeInterface $big_pipe) {
+    $this->bigPipe = $big_pipe;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function sendContent() {
+    $this->bigPipe->sendContent($this->content, $this->bigPipePlaceholders);
+
+    return $this;
+  }
+}
diff --git a/core/modules/big_pipe/src/Render/Placeholder/BigPipeStrategy.php b/core/modules/big_pipe/src/Render/Placeholder/BigPipeStrategy.php
new file mode 100644
index 0000000..ad369af
--- /dev/null
+++ b/core/modules/big_pipe/src/Render/Placeholder/BigPipeStrategy.php
@@ -0,0 +1,102 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\big_pipe\Render\Placeholder\BigPipeStrategy
+ */
+
+namespace Drupal\big_pipe\Render\Placeholder;
+
+use Drupal\Component\Utility\Crypt;
+use Drupal\Component\Utility\Html;
+use Drupal\Core\Render\Placeholder\PlaceholderStrategyInterface;
+use Drupal\Core\Session\AccountInterface;
+
+/**
+ * Defines the 'big_pipe' render strategy.
+ *
+ * This is the last strategy that always replaces all remaining placeholders.
+ */
+class BigPipeStrategy implements PlaceholderStrategyInterface {
+
+  /**
+   * The current user.
+   *
+   * @var \Drupal\Core\Session\AccountInterface
+   */
+  protected $currentUser;
+
+  /**
+   * Constructs a new BigPipeStrategy class.
+   *
+   * @param \Drupal\Core\Session\AccountInterface $current_user
+   *   The current user.
+   */
+  public function __construct(AccountInterface $current_user) {
+    $this->currentUser = $current_user;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processPlaceholders(array $placeholders) {
+    $return = [];
+
+    // @todo Move to a ResponsePolicy instead.
+    // @todo Add user.roles:authenticated cache context.
+    if (!$this->currentUser->isAuthenticated()) {
+      return $return;
+    }
+
+    // @todo Add user.permissions cache context.
+    if (!$this->currentUser->hasPermission('Use BigPipe placeholder strategy')) {
+      return $return;
+    }
+
+    // @todo Add 'session' cache context.
+    if (empty($_SESSION['big_pipe_has_js'])) {
+      return $return;
+    }
+
+    // Ensure placeholders are unique per page.
+    $token = Crypt::randomBytesBase64(55);
+
+    foreach ($placeholders as $placeholder => $placeholder_elements) {
+      // Blacklist some #lazy_builder callbacks.
+      // @todo Use #create_placeholder_options instead.
+      if (isset($placeholder_elements['#lazy_builder'][0])) {
+        // CSRF tokens are part of other HTML elements; do not BigPipe those.
+        if ($placeholder_elements['#lazy_builder'][0] == 'route_processor_csrf:renderPlaceholderCsrfToken') {
+          continue;
+        }
+        // The messages element is not able to update the session when BigPipe runs.
+        if ($placeholder_elements['#lazy_builder'][0] == 'Drupal\Core\Render\Element\StatusMessages::renderMessages') {
+          continue;
+        }
+      }
+      $html_placeholder = Html::getId($placeholder . '-' . $token);
+      $return[$placeholder] = [
+         '#markup' => '<div data-big-pipe-selector="' . $html_placeholder . '"></div>',
+         // Big Pipe placeholders are not cacheable.
+         '#cache' => [
+           'max-age' => 0,
+         ],
+         '#attached' => [
+           // Use the big_pipe library.
+           'library' => [
+             'big_pipe/big_pipe',
+           ],
+           // Add the placeholder to a white list of JS processed placeholders.
+           'drupalSettings' => [
+             'bigPipePlaceholders' => [ $html_placeholder => TRUE ],
+           ],
+           'big_pipe_placeholders' => [
+             $html_placeholder => $placeholder_elements,
+           ],
+         ],
+      ];
+    }
+
+    return $return;
+  }
+}