core/core.services.yml                             |  5 ++
 .../Core/Template/Loader/ThemeRegistryLoader.php   | 68 ++++++++++++++++++++++
 .../src/Tests/Theme/TwigRegistryLoaderTest.php     |  8 +++
 3 files changed, 81 insertions(+)

diff --git a/core/core.services.yml b/core/core.services.yml
index 3fdc792..e89175e 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -1541,6 +1541,11 @@ services:
     arguments: ['@app.root', '@module_handler', '@theme_handler']
     tags:
       - { name: twig.loader, priority: 100 }
+  twig.loader.theme_registry:
+    class: Drupal\Core\Template\Loader\ThemeRegistryLoader
+    arguments: ['@theme.registry']
+    tags:
+      - { name: twig.loader, priority: 0 }
   twig.loader.string:
     class: Drupal\Core\Template\Loader\StringLoader
     tags:
diff --git a/core/lib/Drupal/Core/Template/Loader/ThemeRegistryLoader.php b/core/lib/Drupal/Core/Template/Loader/ThemeRegistryLoader.php
new file mode 100644
index 0000000..67a82dd
--- /dev/null
+++ b/core/lib/Drupal/Core/Template/Loader/ThemeRegistryLoader.php
@@ -0,0 +1,68 @@
+<?php
+
+namespace Drupal\Core\Template\Loader;
+
+use Drupal\Core\Theme\Registry;
+
+/**
+ * Loads templates based on information from the Drupal theme registry.
+ *
+ * Allows for template inheritance based on the currently active template.
+ */
+class ThemeRegistryLoader extends \Twig_Loader_Filesystem {
+
+  /**
+   * The theme registry used to determine which template to use.
+   *
+   * @var \Drupal\Core\Theme\Registry
+   */
+  protected $themeRegistry;
+
+  /**
+   * Constructs a new ThemeRegistryLoader object.
+   *
+   * @param \Drupal\Core\Theme\Registry $theme_registry
+   *   The theme registry.
+   */
+  public function __construct(Registry $theme_registry) {
+    $this->themeRegistry = $theme_registry;
+  }
+
+  /**
+   * Finds the path to the requested template.
+   *
+   * @param string $name
+   *   The name of the template to load.
+   * @param bool $throw
+   *   Whether to throw an exception when an error occurs.
+   *
+   * @return string
+   *   The path to the template.
+   *
+   * @throws \Twig_Error_Loader
+   *   Thrown if a template matching $name cannot be found.
+   */
+  protected function findTemplate($name, $throw = TRUE) {
+    // Allow for loading based on the Drupal theme registry.
+    $hook = str_replace('.html.twig', '', strtr($name, '-', '_'));
+    $theme_registry = $this->themeRegistry->getRuntime();
+
+    if ($theme_registry->has($hook)) {
+      $info = $theme_registry->get($hook);
+      if (isset($info['path'])) {
+        $path = $info['path'] . '/' . $name;
+      }
+      elseif (isset($info['template'])) {
+        $path = $info['template'] . '.html.twig';
+      }
+      if (isset($path) && is_file($path)) {
+        return $this->cache[$name] = $path;
+      }
+    }
+
+    if ($throw) {
+      throw new \Twig_Error_Loader(sprintf('Unable to find template "%s" in the Drupal theme registry.', $name));
+    }
+  }
+
+}
diff --git a/core/modules/system/src/Tests/Theme/TwigRegistryLoaderTest.php b/core/modules/system/src/Tests/Theme/TwigRegistryLoaderTest.php
index 05b7b30..d90a484 100644
--- a/core/modules/system/src/Tests/Theme/TwigRegistryLoaderTest.php
+++ b/core/modules/system/src/Tests/Theme/TwigRegistryLoaderTest.php
@@ -29,6 +29,7 @@ class TwigRegistryLoaderTest extends WebTestBase {
   protected function setUp() {
     parent::setUp();
     \Drupal::service('theme_handler')->install(array('test_theme_twig_registry_loader', 'test_theme_twig_registry_loader_theme', 'test_theme_twig_registry_loader_subtheme'));
+    $this->twig = \Drupal::service('twig');
   }
 
   /**
@@ -38,6 +39,13 @@ public function assertTwigTemplate($value, $message = '', $group = 'Other') {
     $this->assertTrue($value instanceof \Twig_Template, $message, $group);
   }
 
+  /**
+   * Tests template discovery using the Drupal theme registry.
+   */
+  public function testTemplateDiscovery() {
+    $this->assertTwigTemplate($this->twig->resolveTemplate('block.html.twig'), 'Found block.html.twig in block module.');
+  }
+
   /**
    * Tests template extension and includes using the Drupal theme registry.
    */