diff --git a/core/lib/Drupal/Core/Plugin/Discovery/YamlDiscovery.php b/core/lib/Drupal/Core/Plugin/Discovery/YamlDiscovery.php
new file mode 100644
index 0000000..872b6e2
--- /dev/null
+++ b/core/lib/Drupal/Core/Plugin/Discovery/YamlDiscovery.php
@@ -0,0 +1,64 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\Core\Plugin\Discovery\YamlDiscovery.
+ */
+
+namespace Drupal\Core\Plugin\Discovery;
+
+use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
+use Drupal\Component\Discovery\YamlDiscovery as DrupalYamlDiscovery;
+
+/**
+ * Allows YAML files to define plugin definitions.
+ */
+class YamlDiscovery implements DiscoveryInterface {
+
+  /**
+   * Internal YAML parsing handler.
+   *
+   * @var \Drupal\Component\Discovery\YamlDiscovery
+   */
+  protected $discovery;
+
+  /**
+   * Construct a YamlDiscovery object.
+   *
+   * @param string $name
+   *   The file name suffix to use for discovery. E.g. 'test' will become
+   *   'MODULE.test.yml'.
+   * @param array $directories
+   *   An array of directories to scan.
+   */
+  function __construct($name, array $directories) {
+    $this->discovery = new DrupalYamlDiscovery($name, $directories);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDefinition($plugin_id) {
+    $definitions = $this->getDefinitions();
+    return isset($definitions[$plugin_id]) ? $definitions[$plugin_id] : NULL;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDefinitions() {
+    $plugins = $this->discovery->findAll();
+
+    // Flatten definitions into what's expected from plugins.
+    $definitions = array();
+    foreach ($plugins as $provider => $list) {
+      foreach ($list as $id => $tmp) {
+        $definitions[$id] = $tmp + array(
+          'provider' => $provider,
+        );
+      }
+    }
+
+    return $definitions;
+  }
+}
diff --git a/core/lib/Drupal/Core/Plugin/Discovery/YamlDiscoveryDecorator.php b/core/lib/Drupal/Core/Plugin/Discovery/YamlDiscoveryDecorator.php
new file mode 100644
index 0000000..df973f5
--- /dev/null
+++ b/core/lib/Drupal/Core/Plugin/Discovery/YamlDiscoveryDecorator.php
@@ -0,0 +1,50 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Plugin\Discovery\YamlDiscoveryDecorator.
+ */
+
+namespace Drupal\Core\Plugin\Discovery;
+
+class YamlDiscoveryDecorator extends YamlDiscovery {
+
+  /**
+   * The Discovery object being decorated.
+   *
+   * @var \Drupal\Component\Plugin\Discovery\DiscoveryInterface
+   */
+  protected $decorated;
+
+  /**
+   * Constructs a \Drupal\Component\Plugin\Discovery\StaticDiscoveryDecorator object.
+   *
+   * @param \Drupal\Component\Plugin\Discovery\DiscoveryInterface $decorated
+   *   The discovery object that is being decorated.
+   * @param string $name
+   *   The file name suffix to use for discovery. E.g. 'test' will become
+   *   'MODULE.test.yml'.
+   * @param array $directories
+   *   An array of directories to scan.
+   */
+  public function __construct(DiscoveryInterface $decorated, $name, array $directories) {
+    parent::__construct($name, $directories);
+
+    $this->decorated = $decorated;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDefinitions() {
+    return $this->getDefinitions() + $this->decorated->getDefinitions();
+  }
+
+  /**
+   * Passes through all unknown calls onto the decorated object
+   */
+  public function __call($method, $args) {
+    return call_user_func_array(array($this->decorated, $method), $args);
+  }
+
+}