.../Core/Render/StreamedResponseInterface.php      | 17 +++++
 core/modules/big_pipe/big_pipe.services.yml        |  5 --
 .../big_pipe/src/PageCache/DenyBigPipeResponse.php | 24 -------
 .../page_cache/src/StackMiddleware/PageCache.php   | 79 +++++++++++++++-------
 .../modules/page_cache/src/Tests/PageCacheTest.php | 28 +++++++-
 .../page_cache_form_test.info.yml                  |  0
 .../page_cache_form_test.install                   |  0
 .../page_cache_form_test.module                    |  0
 .../page_cache_form_test.routing.yml               |  0
 .../src/Form/TestForm.php                          |  0
 .../page_cache_test/page_cache_test.info.yml       |  6 ++
 .../page_cache_test/page_cache_test.routing.yml    | 19 ++++++
 .../src/PageCacheTestController.php                | 31 +++++++++
 .../src/PageCacheTestStreamedResponse.php          | 25 +++++++
 14 files changed, 181 insertions(+), 53 deletions(-)

diff --git a/core/lib/Drupal/Core/Render/StreamedResponseInterface.php b/core/lib/Drupal/Core/Render/StreamedResponseInterface.php
new file mode 100644
index 0000000..524e1d5
--- /dev/null
+++ b/core/lib/Drupal/Core/Render/StreamedResponseInterface.php
@@ -0,0 +1,17 @@
+<?php
+
+namespace Drupal\Core\Render;
+
+/**
+ * Defines an interface for streamed responses.
+ */
+interface StreamedResponseInterface {
+
+  /**
+   * Returns the entire streamed response, if possible.
+   *
+   * @return FALSE|\Symfony\Component\HttpFoundation\Response
+   */
+  public function getStreamedResponse();
+
+}
diff --git a/core/modules/big_pipe/big_pipe.services.yml b/core/modules/big_pipe/big_pipe.services.yml
index 82a0c73..5235037 100644
--- a/core/modules/big_pipe/big_pipe.services.yml
+++ b/core/modules/big_pipe/big_pipe.services.yml
@@ -23,8 +23,3 @@ services:
     class: Drupal\big_pipe\EventSubscriber\NoBigPipeRouteAlterSubscriber
     tags:
       - { name: event_subscriber }
-
-  big_pipe.page_cache:
-    class: Drupal\big_pipe\PageCache\DenyBigPipeResponse
-    tags:
-      - { name: page_cache_response_policy }
diff --git a/core/modules/big_pipe/src/PageCache/DenyBigPipeResponse.php b/core/modules/big_pipe/src/PageCache/DenyBigPipeResponse.php
deleted file mode 100644
index 9fd5e2c..0000000
--- a/core/modules/big_pipe/src/PageCache/DenyBigPipeResponse.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-namespace Drupal\big_pipe\PageCache;
-
-use Drupal\big_pipe\Render\BigPipeResponse;
-use Drupal\Core\PageCache\ResponsePolicyInterface;
-use Symfony\Component\HttpFoundation\Request;
-use Symfony\Component\HttpFoundation\Response;
-
-/**
- * A policy evaluating to static::DENY when a BigPipe response is delivered.
- */
-class DenyBigPipeResponse implements ResponsePolicyInterface {
-
-  /**
-   * {@inheritdoc}
-   */
-  public function check(Response $response, Request $request) {
-    if ($response instanceof BigPipeResponse) {
-      return static::DENY;
-    }
-  }
-
-}
diff --git a/core/modules/page_cache/src/StackMiddleware/PageCache.php b/core/modules/page_cache/src/StackMiddleware/PageCache.php
index 1071739..828ec34 100644
--- a/core/modules/page_cache/src/StackMiddleware/PageCache.php
+++ b/core/modules/page_cache/src/StackMiddleware/PageCache.php
@@ -7,16 +7,18 @@
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\PageCache\RequestPolicyInterface;
 use Drupal\Core\PageCache\ResponsePolicyInterface;
+use Drupal\Core\Render\StreamedResponseInterface;
 use Symfony\Component\HttpFoundation\BinaryFileResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpFoundation\StreamedResponse;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
+use Symfony\Component\HttpKernel\TerminableInterface;
 
 /**
  * Executes the page caching before the main kernel takes over the request.
  */
-class PageCache implements HttpKernelInterface {
+class PageCache implements HttpKernelInterface, TerminableInterface {
 
   /**
    * The wrapped HTTP kernel.
@@ -80,6 +82,19 @@ public function handle(Request $request, $type = self::MASTER_REQUEST, $catch =
     return $response;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function terminate(Request $request, Response $response) {
+    // Also cache streamed responses, if they support it.
+    if ($response instanceof StreamedResponseInterface) {
+      $streamed_response = $response->getStreamedResponse();
+      if ($streamed_response !== FALSE) {
+        $this->storeResponse($request, $streamed_response);
+      }
+    }
+  }
+
   /**
    * Sidesteps the page cache and directly forwards a request to the backend.
    *
@@ -205,6 +220,43 @@ protected function fetch(Request $request, $type = self::MASTER_REQUEST, $catch
     /** @var \Symfony\Component\HttpFoundation\Response $response */
     $response = $this->httpKernel->handle($request, $type, $catch);
 
+    // Currently it is not possible to cache binary file or streamed responses:
+    // https://github.com/symfony/symfony/issues/9128#issuecomment-25088678.
+    // Therefore exclude them, even for subclasses that implement
+    // CacheableResponseInterface.
+    if ($response instanceof BinaryFileResponse || $response instanceof StreamedResponse) {
+      return $response;
+    }
+    // The exception: streamed responses that implement
+    // StreamedResponseInterface: those can be cached by PageCache during the
+    // 'terminate' phase/event. Already set the 'X-Drupal-Cache' header, so that
+    // header is present as expected.
+    // @see ::terminate()
+    elseif ($response instanceof StreamedResponseInterface) {
+      // Mark response as a cache miss.
+      $response->headers->set('X-Drupal-Cache', 'MISS');
+      return $response;
+    }
+
+    // Allow policy rules to further restrict which responses to cache.
+    if ($this->responsePolicy->check($response, $request) === ResponsePolicyInterface::DENY) {
+      return $response;
+    }
+
+    $this->storeResponse($request, $response);
+
+    return $response;
+  }
+
+  /**
+   * Stores a response in the page cache.
+   *
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   A request object.
+   * @param \Symfony\Component\HttpFoundation\Response $response
+   *   A response object that should be stored in the page cache.
+   */
+  protected function storeResponse(Request $request, Response $response) {
     // Drupal's primary cache invalidation architecture is cache tags: any
     // response that varies by a configuration value or data in a content
     // entity should have cache tags, to allow for instant cache invalidation
@@ -227,27 +279,7 @@ protected function fetch(Request $request, $type = self::MASTER_REQUEST, $catch
     //   so by replacing/extending this middleware service or adding another
     //   one.
     if (!$response instanceof CacheableResponseInterface) {
-      return $response;
-    }
-
-    // Mark response as a cache miss.
-    $response->headers->set('X-Drupal-Cache', 'MISS');
-
-    // Currently it is not possible to cache binary file or streamed responses:
-    // https://github.com/symfony/symfony/issues/9128#issuecomment-25088678.
-    // Therefore exclude them, even for subclasses that implement
-    // CacheableResponseInterface.
-    if ($response instanceof BinaryFileResponse || $response instanceof StreamedResponse) {
-      return $response;
-    }
-
-    // Allow policy rules to further restrict which responses to cache.
-    // @todo supporting BigPipe means that we return early here, which means
-    // that none of the code below runs. Thus:
-    // - page cache response policies won't work for BigPipe (which I guess can be okay since we need to duplicate that part of the page cache code in BigPipe anyway, because we need to assemble the final non-BigPipe response from it and then store it in Page Cache
-    // - for the same reason, we need to handle all the other logic below: 4xx responses cache tags + expiration date
-    if ($this->responsePolicy->check($response, $request) === ResponsePolicyInterface::DENY) {
-      return $response;
+      return;
     }
 
     // The response passes all of the above checks, so cache it.
@@ -260,7 +292,8 @@ protected function fetch(Request $request, $type = self::MASTER_REQUEST, $catch
     $expire = ($date > time()) ? $date : Cache::PERMANENT;
     $this->set($request, $response, $expire, $tags);
 
-    return $response;
+    // Mark response as a cache miss.
+    $response->headers->set('X-Drupal-Cache', 'MISS');
   }
 
   /**
diff --git a/core/modules/page_cache/src/Tests/PageCacheTest.php b/core/modules/page_cache/src/Tests/PageCacheTest.php
index 44c94e1..10a1770 100644
--- a/core/modules/page_cache/src/Tests/PageCacheTest.php
+++ b/core/modules/page_cache/src/Tests/PageCacheTest.php
@@ -24,7 +24,7 @@ class PageCacheTest extends WebTestBase {
    *
    * @var array
    */
-  public static $modules = array('test_page_test', 'system_test', 'entity_test');
+  public static $modules = array('test_page_test', 'system_test', 'entity_test', 'page_cache_test');
 
   /**
    * {@inheritdoc}
@@ -484,4 +484,30 @@ public function testCacheableResponseResponses() {
     $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
   }
 
+  /**
+   * Tests Page Cache's support for streamed responses.
+   *
+   * @see \Drupal\page_cache\StackMiddleware\PageCache::terminate()
+   */
+  public function testStreamedResponses() {
+    // Symfony streamed response: not even considered.
+    $this->drupalGet(Url::fromRoute('page_cache_test.symfony_streamed_response'));
+    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->drupalGet(Url::fromRoute('page_cache_test.symfony_streamed_response'));
+    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+
+    // StreamedResponseInterface Response, with untracked stream: always cache
+    // miss.
+    $this->drupalGet(Url::fromRoute('page_cache_test.streamed_response_interface.untracked'));
+    $this->assertIdentical('MISS', $this->drupalGetHeader('X-Drupal-Cache'));
+    $this->drupalGet(Url::fromRoute('page_cache_test.streamed_response_interface.untracked'));
+    $this->assertIdentical('MISS', $this->drupalGetHeader('X-Drupal-Cache'));
+
+    // StreamedResponseInterface Response, with tracked stream: cacheable.
+    $this->drupalGet(Url::fromRoute('page_cache_test.streamed_response_interface.tracked'));
+    $this->assertIdentical('MISS', $this->drupalGetHeader('X-Drupal-Cache'));
+    $this->drupalGet(Url::fromRoute('page_cache_test.streamed_response_interface.tracked'));
+    $this->assertIdentical('HIT', $this->drupalGetHeader('X-Drupal-Cache'));
+  }
+
 }
diff --git a/core/modules/page_cache/tests/modules/page_cache_form_test.info.yml b/core/modules/page_cache/tests/modules/page_cache_form_test/page_cache_form_test.info.yml
similarity index 100%
rename from core/modules/page_cache/tests/modules/page_cache_form_test.info.yml
rename to core/modules/page_cache/tests/modules/page_cache_form_test/page_cache_form_test.info.yml
diff --git a/core/modules/page_cache/tests/modules/page_cache_form_test.install b/core/modules/page_cache/tests/modules/page_cache_form_test/page_cache_form_test.install
similarity index 100%
rename from core/modules/page_cache/tests/modules/page_cache_form_test.install
rename to core/modules/page_cache/tests/modules/page_cache_form_test/page_cache_form_test.install
diff --git a/core/modules/page_cache/tests/modules/page_cache_form_test.module b/core/modules/page_cache/tests/modules/page_cache_form_test/page_cache_form_test.module
similarity index 100%
rename from core/modules/page_cache/tests/modules/page_cache_form_test.module
rename to core/modules/page_cache/tests/modules/page_cache_form_test/page_cache_form_test.module
diff --git a/core/modules/page_cache/tests/modules/page_cache_form_test.routing.yml b/core/modules/page_cache/tests/modules/page_cache_form_test/page_cache_form_test.routing.yml
similarity index 100%
rename from core/modules/page_cache/tests/modules/page_cache_form_test.routing.yml
rename to core/modules/page_cache/tests/modules/page_cache_form_test/page_cache_form_test.routing.yml
diff --git a/core/modules/page_cache/tests/modules/src/Form/TestForm.php b/core/modules/page_cache/tests/modules/page_cache_form_test/src/Form/TestForm.php
similarity index 100%
rename from core/modules/page_cache/tests/modules/src/Form/TestForm.php
rename to core/modules/page_cache/tests/modules/page_cache_form_test/src/Form/TestForm.php
diff --git a/core/modules/page_cache/tests/modules/page_cache_test/page_cache_test.info.yml b/core/modules/page_cache/tests/modules/page_cache_test/page_cache_test.info.yml
new file mode 100644
index 0000000..bef43eb
--- /dev/null
+++ b/core/modules/page_cache/tests/modules/page_cache_test/page_cache_test.info.yml
@@ -0,0 +1,6 @@
+name: 'Page Cache Test'
+type: module
+description: 'Support module for the Page Cache module tests.'
+core: 8.x
+package: Testing
+version: VERSION
diff --git a/core/modules/page_cache/tests/modules/page_cache_test/page_cache_test.routing.yml b/core/modules/page_cache/tests/modules/page_cache_test/page_cache_test.routing.yml
new file mode 100644
index 0000000..5f72632
--- /dev/null
+++ b/core/modules/page_cache/tests/modules/page_cache_test/page_cache_test.routing.yml
@@ -0,0 +1,19 @@
+page_cache_test.symfony_streamed_response:
+  path: '/page_cache_test/symfony_streamedresponse'
+  defaults:
+    _controller: '\Drupal\page_cache_test\PageCacheTestController::symfonyStreamedResponse'
+  requirements:
+    _access: 'TRUE'
+
+page_cache_test.streamed_response_interface.untracked:
+  path: '/page_cache_test/streamed_response_interface/untracked'
+  defaults:
+    _controller: '\Drupal\page_cache_test\PageCacheTestController::streamedResponseInterfaceUntracked'
+  requirements:
+    _access: 'TRUE'
+page_cache_test.streamed_response_interface.tracked:
+  path: '/page_cache_test/streamed_response_interface/tracked'
+  defaults:
+    _controller: '\Drupal\page_cache_test\PageCacheTestController::streamedResponseInterfaceTracked'
+  requirements:
+    _access: 'TRUE'
diff --git a/core/modules/page_cache/tests/modules/page_cache_test/src/PageCacheTestController.php b/core/modules/page_cache/tests/modules/page_cache_test/src/PageCacheTestController.php
new file mode 100644
index 0000000..17d014f
--- /dev/null
+++ b/core/modules/page_cache/tests/modules/page_cache_test/src/PageCacheTestController.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace Drupal\page_cache_test;
+
+use Drupal\Core\Render\HtmlResponse;
+use Symfony\Component\HttpFoundation\StreamedResponse;
+
+class PageCacheTestController {
+
+  /**
+   * Returns a Symfony streamed response.
+   */
+  public function symfonyStreamedResponse() {
+    return new StreamedResponse(function () { echo 'Symfony streamed response'; });
+  }
+
+  /**
+   * Returns a StreamedResponseInterface Response, with untracked stream.
+   */
+  public function streamedResponseInterfaceUntracked() {
+    return new PageCacheTestStreamedResponse(FALSE);
+  }
+
+  /**
+   * Returns a StreamedResponseInterface Response, with tracked stream.
+   */
+  public function streamedResponseInterfaceTracked() {
+    return new PageCacheTestStreamedResponse((new HtmlResponse('Hello world!'))->setExpires(\DateTime::createFromFormat('j-M-Y H:i:s T', '19-Nov-1978 05:00:00 UTC')));
+  }
+
+}
diff --git a/core/modules/page_cache/tests/modules/page_cache_test/src/PageCacheTestStreamedResponse.php b/core/modules/page_cache/tests/modules/page_cache_test/src/PageCacheTestStreamedResponse.php
new file mode 100644
index 0000000..5e20353
--- /dev/null
+++ b/core/modules/page_cache/tests/modules/page_cache_test/src/PageCacheTestStreamedResponse.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace Drupal\page_cache_test;
+
+
+use Drupal\Core\Cache\CacheableResponseInterface;
+use Drupal\Core\Cache\CacheableResponseTrait;
+use Drupal\Core\Render\StreamedResponseInterface;
+use Symfony\Component\HttpFoundation\Response;
+
+class PageCacheTestStreamedResponse extends Response implements StreamedResponseInterface, CacheableResponseInterface {
+
+  use CacheableResponseTrait;
+
+  protected $streamedResponse;
+
+  public function __construct($streamed_response) {
+    $this->streamedResponse = $streamed_response;
+    parent::__construct('', 200, []);
+  }
+
+  public function getStreamedResponse() {
+    return $this->streamedResponse;
+  }
+}