diff --git a/core/core.services.yml b/core/core.services.yml
index 31167bd..e405ac6 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -68,18 +68,18 @@ services:
     factory_service: cache_factory
     arguments: [path]
   cache_tag_factory:
-    class: Drupal\Core\Cache\CacheTagFactory
+    class: Drupal\Core\Cache\CacheTagBackendFactory
     arguments: ['@settings']
     calls:
       - [setContainer, ['@service_container']]
   cache.tag.database:
-    class: Drupal\Core\Cache\DatabaseTag
+    class: Drupal\Core\Cache\DatabaseTagBackend
     arguments: ['@database']
     tags:
       - { name: cache.tag }
       - { name: persist }
   cache.tag.memory:
-    class: Drupal\Core\Cache\MemoryTag
+    class: Drupal\Core\Cache\MemoryTagBackend
     tags:
       - { name: cache.tag }
       - { name: persist }
diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index c70360b..a69df30 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -382,7 +382,7 @@ function install_begin_request(&$install_state) {
       ->addArgument(new Reference('event_dispatcher'))
       ->addArgument(new Reference('config.typed'));
 
-    $container->register('cache.tag.memory', 'Drupal\Core\Cache\MemoryTag');
+    $container->register('cache.tag.memory', 'Drupal\Core\Cache\MemoryTagBackend');
 
     // Register the 'language_manager' service.
     $container->register('language_manager', 'Drupal\Core\Language\LanguageManager')
diff --git a/core/lib/Drupal/Core/Cache/CacheBackendInterface.php b/core/lib/Drupal/Core/Cache/CacheBackendInterface.php
index de49e8c..234d1f1 100644
--- a/core/lib/Drupal/Core/Cache/CacheBackendInterface.php
+++ b/core/lib/Drupal/Core/Cache/CacheBackendInterface.php
@@ -161,7 +161,7 @@ public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = array
    *
    * @see \Drupal\Core\Cache\CacheBackendInterface::invalidate()
    * @see \Drupal\Core\Cache\CacheBackendInterface::deleteMultiple()
-   * @see \Drupal\Core\Cache\CacheTagInterface::deleteTags()
+   * @see \Drupal\Core\Cache\CacheTagBackendInterface::deleteTags()
    * @see \Drupal\Core\Cache\CacheBackendInterface::deleteAll()
    */
   public function delete($cid);
@@ -180,7 +180,7 @@ public function delete($cid);
    *
    * @see \Drupal\Core\Cache\CacheBackendInterface::invalidateMultiple()
    * @see \Drupal\Core\Cache\CacheBackendInterface::delete()
-   * @see \Drupal\Core\Cache\CacheTagInterface::deleteTags()
+   * @see \Drupal\Core\Cache\CacheTagBackendInterface::deleteTags()
    * @see \Drupal\Core\Cache\CacheBackendInterface::deleteAll()
    */
   public function deleteMultiple(array $cids);
@@ -191,7 +191,7 @@ public function deleteMultiple(array $cids);
    * @see \Drupal\Core\Cache\CacheBackendInterface::invalidateAll()
    * @see \Drupal\Core\Cache\CacheBackendInterface::delete()
    * @see \Drupal\Core\Cache\CacheBackendInterface::deleteMultiple()
-   * @see \Drupal\Core\Cache\CacheTagInterface::deleteTags()
+   * @see \Drupal\Core\Cache\CacheTagBackendInterface::deleteTags()
    */
   public function deleteAll();
 
@@ -206,7 +206,7 @@ public function deleteAll();
    *
    * @see \Drupal\Core\Cache\CacheBackendInterface::delete()
    * @see \Drupal\Core\Cache\CacheBackendInterface::invalidateMultiple()
-   * @see \Drupal\Core\Cache\CacheTagInterface::invalidateTags()
+   * @see \Drupal\Core\Cache\CacheTagBackendInterface::invalidateTags()
    * @see \Drupal\Core\Cache\CacheBackendInterface::invalidateAll()
    */
   public function invalidate($cid);
@@ -222,7 +222,7 @@ public function invalidate($cid);
    *
    * @see \Drupal\Core\Cache\CacheBackendInterface::deleteMultiple()
    * @see \Drupal\Core\Cache\CacheBackendInterface::invalidate()
-   * @see \Drupal\Core\Cache\CacheTagInterface::invalidateTags()
+   * @see \Drupal\Core\Cache\CacheTagBackendInterface::invalidateTags()
    * @see \Drupal\Core\Cache\CacheBackendInterface::invalidateAll()
    */
   public function invalidateMultiple(array $cids);
@@ -239,7 +239,7 @@ public function invalidateMultiple(array $cids);
    * @see \Drupal\Core\Cache\CacheBackendInterface::deleteAll()
    * @see \Drupal\Core\Cache\CacheBackendInterface::invalidate()
    * @see \Drupal\Core\Cache\CacheBackendInterface::invalidateMultiple()
-   * @see \Drupal\Core\Cache\CacheTagInterface::invalidateTags()
+   * @see \Drupal\Core\Cache\CacheTagBackendInterface::invalidateTags()
    */
   public function invalidateAll();
 
diff --git a/core/lib/Drupal/Core/Cache/CacheTagBackendBase.php b/core/lib/Drupal/Core/Cache/CacheTagBackendBase.php
new file mode 100644
index 0000000..23b007d
--- /dev/null
+++ b/core/lib/Drupal/Core/Cache/CacheTagBackendBase.php
@@ -0,0 +1,62 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Cache\CacheTagBase.
+ */
+
+namespace Drupal\Core\Cache;
+
+/**
+ * Class CacheTagBase
+ */
+abstract class CacheTagBackendBase implements CacheTagBackendInterface {
+
+  /**
+   * 'Flattens' a tags array into an array of strings.
+   *
+   * @param array $tags
+   *   Associative array of tags to flatten.
+   *
+   * @return array
+   *   An indexed array of flattened tag identifiers.
+   */
+  public function flattenTags(array $tags) {
+    if (isset($tags[0])) {
+      return $tags;
+    }
+
+    $flat_tags = array();
+    foreach ($tags as $namespace => $values) {
+      if (is_array($values)) {
+        foreach ($values as $value) {
+          $flat_tags[] = "$namespace:$value";
+        }
+      }
+      else {
+        $flat_tags[] = "$namespace:$values";
+      }
+    }
+    return $flat_tags;
+  }
+
+  /**
+   * Raises an array of 'flattened' tags (inverse function to flattenTags()).
+   *
+   * @param array $tags
+   *   Associative array of flat tags to raise.
+   *
+   * @return array
+   *   An array of raised tags.
+   */
+  public function raiseTags(array $flat_tags) {
+    $tags = array();
+    foreach ($flat_tags as $tag) {
+      list($key, $value) = explode(':', $tag);
+      $tags[$key] = $value;
+    }
+
+    return $tags;
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Cache/CacheTagBackendFactory.php b/core/lib/Drupal/Core/Cache/CacheTagBackendFactory.php
new file mode 100644
index 0000000..a632449
--- /dev/null
+++ b/core/lib/Drupal/Core/Cache/CacheTagBackendFactory.php
@@ -0,0 +1,57 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Cache\CacheTagFactory.
+ */
+
+namespace Drupal\Core\Cache;
+
+use Drupal\Component\Utility\Settings;
+use Symfony\Component\DependencyInjection\ContainerAware;
+
+/**
+ * Defines a cache tag backend factory.
+ */
+class CacheTagBackendFactory extends ContainerAware {
+
+  /**
+   * The settings array.
+   *
+   * @var \Drupal\Component\Utility\Settings
+   */
+  protected $settings;
+
+  /**
+   * Constructs CacheTagBackendFactory object.
+   *
+   * @param \Drupal\Component\Utility\Settings $settings
+   *   The settings array.
+   */
+  function __construct(Settings $settings) {
+    $this->settings = $settings;
+  }
+
+  /**
+   * Instantiates a cache tag class.
+   *
+   * By default, this returns an instance of the
+   * Drupal\Core\Cache\DatabaseBackendTag class.
+   *
+   * @return \Drupal\Core\Cache\CacheTagBackendInterface
+   *   The cache tag instance.
+   */
+  public function get() {
+    $cache_tag_service = $this->settings->get('cache_tag_service');
+
+    if (isset($cache_tag_service)) {
+      $service_name = $cache_tag_service;
+    }
+    else {
+      $service_name = 'cache.tag.database';
+    }
+
+    return $this->container->get($service_name);
+  }
+
+}
diff --git a/core/lib/Drupal/Core/Cache/CacheTagBackendInterface.php b/core/lib/Drupal/Core/Cache/CacheTagBackendInterface.php
new file mode 100644
index 0000000..7a4a629
--- /dev/null
+++ b/core/lib/Drupal/Core/Cache/CacheTagBackendInterface.php
@@ -0,0 +1,62 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Cache\CacheTagBackendInterface.
+ */
+
+namespace Drupal\Core\Cache;
+
+/**
+ * Class CacheTagBackendInterface.
+ */
+interface CacheTagBackendInterface {
+
+  /**
+   * Marks specified cache tags as deleted.
+   *
+   * If the cache items are being deleted because they are no longer "fresh",
+   * you may consider using invalidateTags() instead. This allows callers to
+   * retrieve the invalid items by calling get() with $allow_invalid set to TRUE.
+   * In some cases an invalid item may be acceptable rather than having to
+   * rebuild the cache.
+   *
+   * @param array $tags
+   *   Associative array of tags.
+   */
+  public function deleteTags(array $tags);
+
+  /**
+   * Marks specified cache tags as invalid.
+   *
+   * @param array $tags
+   *   Associative array of tags.
+   */
+  public function invalidateTags(array $tags);
+
+  /**
+   * Returns the sum total of validations for a given set of tags.
+   *
+   * @param array $tags
+   *   Associative array of tags.
+   * @param bool $set_context
+   *   TRUE if called from set context.
+   * @return array
+   *   Array with two items (invalidations, deletions) providing sum of all
+   *   invalidations/deletions over all provided tags.
+   */
+  public function checksumTags(array $tags, $set_context);
+
+  /**
+   * Prepares cache item before it is returned from cache backend interface.
+   *
+   * $item->deleted should be set to TRUE if item was deleted via tags and
+   * $item->valid should be set to FALSE if item was invalidated.
+   */
+  public function prepareGet(&$item);
+
+  /**
+   * Clears cache tag service internal caches.
+   */
+  public function clearCache();
+}
diff --git a/core/lib/Drupal/Core/Cache/CacheTagBase.php b/core/lib/Drupal/Core/Cache/CacheTagBase.php
deleted file mode 100644
index bfcc211..0000000
--- a/core/lib/Drupal/Core/Cache/CacheTagBase.php
+++ /dev/null
@@ -1,43 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Cache\CacheTagBase.
- */
-
-namespace Drupal\Core\Cache;
-
-/**
- * Class CacheTagBase
- */
-abstract class CacheTagBase implements CacheTagInterface {
-
-  /**
-   * 'Flattens' a tags array into an array of strings.
-   *
-   * @param array $tags
-   *   Associative array of tags to flatten.
-   *
-   * @return array
-   *   An indexed array of flattened tag identifiers.
-   */
-  public function flattenTags(array $tags) {
-    if (isset($tags[0])) {
-      return $tags;
-    }
-
-    $flat_tags = array();
-    foreach ($tags as $namespace => $values) {
-      if (is_array($values)) {
-        foreach ($values as $value) {
-          $flat_tags[] = "$namespace:$value";
-        }
-      }
-      else {
-        $flat_tags[] = "$namespace:$values";
-      }
-    }
-    return $flat_tags;
-  }
-
-}
diff --git a/core/lib/Drupal/Core/Cache/CacheTagFactory.php b/core/lib/Drupal/Core/Cache/CacheTagFactory.php
deleted file mode 100644
index cb9715e..0000000
--- a/core/lib/Drupal/Core/Cache/CacheTagFactory.php
+++ /dev/null
@@ -1,57 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Cache\CacheTagFactory.
- */
-
-namespace Drupal\Core\Cache;
-
-use Drupal\Component\Utility\Settings;
-use Symfony\Component\DependencyInjection\ContainerAware;
-
-/**
- * Defines a cache tag factory.
- */
-class CacheTagFactory extends ContainerAware {
-
-  /**
-   * The settings array.
-   *
-   * @var \Drupal\Component\Utility\Settings
-   */
-  protected $settings;
-
-  /**
-   * Constructs CacheTagFactory object.
-   *
-   * @param \Drupal\Component\Utility\Settings $settings
-   *   The settings array.
-   */
-  function __construct(Settings $settings) {
-    $this->settings = $settings;
-  }
-
-  /**
-   * Instantiates a cache tag class.
-   *
-   * By default, this returns an instance of the
-   * Drupal\Core\Cache\DatabaseTag class.
-   *
-   * @return \Drupal\Core\Cache\CacheTagInterface
-   *   The cache tag instance.
-   */
-  public function get() {
-    $cache_tag_service = $this->settings->get('cache_tag_service');
-
-    if (isset($cache_tag_service)) {
-      $service_name = $cache_tag_service;
-    }
-    else {
-      $service_name = 'cache.tag.database';
-    }
-
-    return $this->container->get($service_name);
-  }
-
-}
diff --git a/core/lib/Drupal/Core/Cache/CacheTagInterface.php b/core/lib/Drupal/Core/Cache/CacheTagInterface.php
deleted file mode 100644
index fac94d7..0000000
--- a/core/lib/Drupal/Core/Cache/CacheTagInterface.php
+++ /dev/null
@@ -1,62 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Cache\CacheTagInterface.
- */
-
-namespace Drupal\Core\Cache;
-
-/**
- * Class CacheTagInterface.
- */
-interface CacheTagInterface {
-
-  /**
-   * Marks specified cache tags as deleted.
-   *
-   * If the cache items are being deleted because they are no longer "fresh",
-   * you may consider using invalidateTags() instead. This allows callers to
-   * retrieve the invalid items by calling get() with $allow_invalid set to TRUE.
-   * In some cases an invalid item may be acceptable rather than having to
-   * rebuild the cache.
-   *
-   * @param array $tags
-   *   Associative array of tags.
-   */
-  public function deleteTags(array $tags);
-
-  /**
-   * Marks specified cache tags as invalid.
-   *
-   * @param array $tags
-   *   Associative array of tags.
-   */
-  public function invalidateTags(array $tags);
-
-  /**
-   * Returns the sum total of validations for a given set of tags.
-   *
-   * @param array $tags
-   *   Associative array of tags.
-   * @param bool $set_context
-   *   TRUE if called from set context.
-   * @return array
-   *   Array with two items (invalidations, deletions) providing sum of all
-   *   invalidations/deletions over all provided tags.
-   */
-  public function checksumTags(array $tags, $set_context);
-
-  /**
-   * Prepares cache item before it is returned from cache backend interface.
-   *
-   * $item->deleted should be set to TRUE if item was deleted via tags and
-   * $item->valid should be set to FALSE if item was invalidated.
-   */
-  public function prepareGet(&$item);
-
-  /**
-   * Clears cache tag service internal caches.
-   */
-  public function clearCache();
-}
diff --git a/core/lib/Drupal/Core/Cache/DatabaseBackend.php b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
index 19ea1b3..2b836fa 100644
--- a/core/lib/Drupal/Core/Cache/DatabaseBackend.php
+++ b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
@@ -33,7 +33,7 @@ class DatabaseBackend implements CacheBackendInterface {
   /**
    * The cache tag service.
    *
-   * @var \Drupal\Core\Cache\CacheTagInterface
+   * @var \Drupal\Core\Cache\CacheTagBackendInterface
    */
   protected $cacheTag;
 
@@ -42,12 +42,12 @@ class DatabaseBackend implements CacheBackendInterface {
    *
    * @param \Drupal\Core\Database\Connection $connection
    *   The database connection.
-   * @param \Drupal\Core\Cache\CacheTagInterface
+   * @param \Drupal\Core\Cache\CacheTagBackendInterface
    *   The cache tag service.
    * @param string $bin
    *   The cache bin for which the object is created.
    */
-  public function __construct(Connection $connection, CacheTagInterface $cache_tag, $bin) {
+  public function __construct(Connection $connection, CacheTagBackendInterface $cache_tag, $bin) {
     // All cache tables should be prefixed with 'cache_', except for the
     // default 'cache' bin.
     if ($bin != 'cache') {
@@ -117,7 +117,7 @@ protected function prepareItem($cache, $allow_invalid) {
       return FALSE;
     }
 
-    $cache->tags = $cache->tags ? explode(' ', $cache->tags) : array();
+    $cache->tags = $cache->tags ? $this->cacheTag->raiseTags(explode(' ', $cache->tags)) : array();
 
     // Check expire time.
     $cache->valid = $time_valid = $cache->expire == Cache::PERMANENT || $cache->expire >= REQUEST_TIME;
diff --git a/core/lib/Drupal/Core/Cache/DatabaseBackendFactory.php b/core/lib/Drupal/Core/Cache/DatabaseBackendFactory.php
index d78f757..7046026 100644
--- a/core/lib/Drupal/Core/Cache/DatabaseBackendFactory.php
+++ b/core/lib/Drupal/Core/Cache/DatabaseBackendFactory.php
@@ -21,7 +21,7 @@ class DatabaseBackendFactory implements CacheFactoryInterface {
   /**
    * The cache tag factory service.
    *
-   * @var \Drupal\Core\Cache\CacheTagFactory
+   * @var \Drupal\Core\Cache\CacheTagBackendFactory
    */
   protected $cacheTagFactory;
 
@@ -30,7 +30,7 @@ class DatabaseBackendFactory implements CacheFactoryInterface {
    *
    * @param \Drupal\Core\Database\Connection $connection
    */
-  function __construct(Connection $connection, CacheTagFactory $cache_tag_factory) {
+  function __construct(Connection $connection, CacheTagBackendFactory $cache_tag_factory) {
     $this->connection = $connection;
     $this->cacheTagFactory = $cache_tag_factory;
   }
diff --git a/core/lib/Drupal/Core/Cache/DatabaseTag.php b/core/lib/Drupal/Core/Cache/DatabaseTag.php
deleted file mode 100644
index a3aeb41..0000000
--- a/core/lib/Drupal/Core/Cache/DatabaseTag.php
+++ /dev/null
@@ -1,159 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Cache\DatabaseTag.
- */
-
-namespace Drupal\Core\Cache;
-
-use Drupal\Core\Database\Connection;
-
-/**
- * Class DatabaseTag.
- */
-class DatabaseTag extends CacheTagBase {
-
-  /**
-   * The database connection.
-   *
-   * @var \Drupal\Core\Database\Connection
-   */
-  protected $connection;
-
-  /**
-   * Constructs a DatabaseTag object.
-   *
-   * @param \Drupal\Core\Database\Connection $connection
-   *   The database connection.
-   */
-  public function __construct(Connection $connection) {
-    $this->connection = $connection;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function invalidateTags(array $tags) {
-    $tag_cache = &drupal_static('Drupal\Core\Cache\CacheTagInterface::tagCache', array());
-    try {
-      foreach ($this->flattenTags($tags) as $tag) {
-        unset($tag_cache[$tag]);
-        $this->connection->merge('cache_tags')
-          ->insertFields(array('invalidations' => 1))
-          ->expression('invalidations', 'invalidations + 1')
-          ->key(array('tag' => $tag))
-          ->execute();
-      }
-    }
-    catch (\Exception $e) {
-      $this->catchException($e, 'cache_tags');
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function deleteTags(array $tags) {
-    $deleted_tags = &drupal_static('Drupal\Core\Cache\DatabaseTag::deletedTags', array());
-    $tag_cache = &drupal_static('Drupal\Core\Cache\CacheTagInterface::tagCache', array());
-    foreach ($this->flattenTags($tags) as $tag) {
-      // Only delete tags once per request unless they are written again.
-      if (isset($deleted_tags[$tag])) {
-        continue;
-      }
-      $deleted_tags[$tag] = TRUE;
-      unset($tag_cache[$tag]);
-      try {
-        $this->connection->merge('cache_tags')
-          ->insertFields(array('deletions' => 1))
-          ->expression('deletions', 'deletions + 1')
-          ->key(array('tag' => $tag))
-          ->execute();
-      }
-      catch (\Exception $e) {
-        $this->catchException($e, 'cache_tags');
-      }
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function checksumTags(array $tags, $set_context) {
-    $flat_tags = $this->flattenTags($tags);
-    $tag_cache = &drupal_static('Drupal\Core\Cache\CacheTagInterface::tagCache', array());
-
-    if ($set_context) {
-      $deleted_tags = &drupal_static('Drupal\Core\Cache\DatabaseTag::deletedTags', array());
-      // Remove tags that were already deleted during this request from the static
-      // cache so that another deletion for them will be correctly updated.
-      foreach ($flat_tags as $tag) {
-        if (isset($deleted_tags[$tag])) {
-          unset($deleted_tags[$tag]);
-        }
-      }
-    }
-
-    $checksum = array(
-      'invalidations' => 0,
-      'deletions' => 0,
-    );
-
-    $query_tags = array_diff($flat_tags, array_keys($tag_cache));
-    if ($query_tags) {
-      $db_tags = $this->connection->query('SELECT tag, invalidations, deletions FROM {cache_tags} WHERE tag IN (:tags)', array(':tags' => $query_tags))->fetchAllAssoc('tag', \PDO::FETCH_ASSOC);
-      $tag_cache += $db_tags;
-
-      // Fill static cache with empty objects for tags not found in the database.
-      $tag_cache += array_fill_keys(array_diff($query_tags, array_keys($db_tags)), $checksum);
-    }
-
-    foreach ($flat_tags as $tag) {
-      $checksum['invalidations'] += $tag_cache[$tag]['invalidations'];
-      $checksum['deletions'] += $tag_cache[$tag]['deletions'];
-    }
-
-    return $checksum;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function prepareGet(&$item) {
-    $checksum = $this->checksumTags($item->tags, FALSE);
-
-    // Check if deleteTags() has been called with any of the entry's tags.
-    $item->deleted = $item->checksum_deletions != $checksum['deletions'];
-
-    // Check if invalidateTags() has been called with any of the entry's tags.
-    if ($item->checksum_invalidations != $checksum['invalidations']) {
-      $item->valid = FALSE;
-    }
-  }
-
-  /**
-   * Act on an exception when cache might be stale.
-   *
-   * If the cache_tags table does not yet exist, that's fine but if the table
-   * exists and yet the query failed, then the cache is stale and the
-   * exception needs to propagate.
-   *
-   * @param $e
-   *   The exception.
-   * @param string|null $table_name
-   *   The table name, defaults to $this->bin. Can be cache_tags.
-   */
-  protected function catchException(\Exception $e, $table_name = NULL) {
-    if ($this->connection->schema()->tableExists($table_name ?: $this->bin)) {
-      throw $e;
-    }
-  }
-
-  /**
-   * {@inheritdoc}.
-   */
-  public function clearCache() {
-    // Nothing to do here.
-  }
-}
diff --git a/core/lib/Drupal/Core/Cache/DatabaseTagBackend.php b/core/lib/Drupal/Core/Cache/DatabaseTagBackend.php
new file mode 100644
index 0000000..7fe2225
--- /dev/null
+++ b/core/lib/Drupal/Core/Cache/DatabaseTagBackend.php
@@ -0,0 +1,159 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Cache\DatabaseTag.
+ */
+
+namespace Drupal\Core\Cache;
+
+use Drupal\Core\Database\Connection;
+
+/**
+ * Class DatabaseTag.
+ */
+class DatabaseTagBackend extends CacheTagBackendBase {
+
+  /**
+   * The database connection.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $connection;
+
+  /**
+   * Constructs a DatabaseTag object.
+   *
+   * @param \Drupal\Core\Database\Connection $connection
+   *   The database connection.
+   */
+  public function __construct(Connection $connection) {
+    $this->connection = $connection;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidateTags(array $tags) {
+    $tag_cache = &drupal_static('Drupal\Core\Cache\CacheTagBackendInterface::tagCache', array());
+    try {
+      foreach ($this->flattenTags($tags) as $tag) {
+        unset($tag_cache[$tag]);
+        $this->connection->merge('cache_tags')
+          ->insertFields(array('invalidations' => 1))
+          ->expression('invalidations', 'invalidations + 1')
+          ->key(array('tag' => $tag))
+          ->execute();
+      }
+    }
+    catch (\Exception $e) {
+      $this->catchException($e, 'cache_tags');
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteTags(array $tags) {
+    $deleted_tags = &drupal_static('Drupal\Core\Cache\DatabaseTagBackend::deletedTags', array());
+    $tag_cache = &drupal_static('Drupal\Core\Cache\CacheTagBackendInterface::tagCache', array());
+    foreach ($this->flattenTags($tags) as $tag) {
+      // Only delete tags once per request unless they are written again.
+      if (isset($deleted_tags[$tag])) {
+        continue;
+      }
+      $deleted_tags[$tag] = TRUE;
+      unset($tag_cache[$tag]);
+      try {
+        $this->connection->merge('cache_tags')
+          ->insertFields(array('deletions' => 1))
+          ->expression('deletions', 'deletions + 1')
+          ->key(array('tag' => $tag))
+          ->execute();
+      }
+      catch (\Exception $e) {
+        $this->catchException($e, 'cache_tags');
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function checksumTags(array $tags, $set_context) {
+    $flat_tags = $this->flattenTags($tags);
+    $tag_cache = &drupal_static('Drupal\Core\Cache\CacheTagBackendInterface::tagCache', array());
+
+    if ($set_context) {
+      $deleted_tags = &drupal_static('Drupal\Core\Cache\DatabaseTagBackend::deletedTags', array());
+      // Remove tags that were already deleted during this request from the static
+      // cache so that another deletion for them will be correctly updated.
+      foreach ($flat_tags as $tag) {
+        if (isset($deleted_tags[$tag])) {
+          unset($deleted_tags[$tag]);
+        }
+      }
+    }
+
+    $checksum = array(
+      'invalidations' => 0,
+      'deletions' => 0,
+    );
+
+    $query_tags = array_diff($flat_tags, array_keys($tag_cache));
+    if ($query_tags) {
+      $db_tags = $this->connection->query('SELECT tag, invalidations, deletions FROM {cache_tags} WHERE tag IN (:tags)', array(':tags' => $query_tags))->fetchAllAssoc('tag', \PDO::FETCH_ASSOC);
+      $tag_cache += $db_tags;
+
+      // Fill static cache with empty objects for tags not found in the database.
+      $tag_cache += array_fill_keys(array_diff($query_tags, array_keys($db_tags)), $checksum);
+    }
+
+    foreach ($flat_tags as $tag) {
+      $checksum['invalidations'] += $tag_cache[$tag]['invalidations'];
+      $checksum['deletions'] += $tag_cache[$tag]['deletions'];
+    }
+
+    return $checksum;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function prepareGet(&$item) {
+    $checksum = $this->checksumTags($item->tags, FALSE);
+
+    // Check if deleteTags() has been called with any of the entry's tags.
+    $item->deleted = $item->checksum_deletions != $checksum['deletions'];
+
+    // Check if invalidateTags() has been called with any of the entry's tags.
+    if ($item->checksum_invalidations != $checksum['invalidations']) {
+      $item->valid = FALSE;
+    }
+  }
+
+  /**
+   * Act on an exception when cache might be stale.
+   *
+   * If the cache_tags table does not yet exist, that's fine but if the table
+   * exists and yet the query failed, then the cache is stale and the
+   * exception needs to propagate.
+   *
+   * @param $e
+   *   The exception.
+   * @param string|null $table_name
+   *   The table name, defaults to $this->bin. Can be cache_tags.
+   */
+  protected function catchException(\Exception $e, $table_name = NULL) {
+    if ($this->connection->schema()->tableExists($table_name ?: $this->bin)) {
+      throw $e;
+    }
+  }
+
+  /**
+   * {@inheritdoc}.
+   */
+  public function clearCache() {
+    // Nothing to do here.
+  }
+}
diff --git a/core/lib/Drupal/Core/Cache/MemoryBackend.php b/core/lib/Drupal/Core/Cache/MemoryBackend.php
index 72cd1ff..9d636f5 100644
--- a/core/lib/Drupal/Core/Cache/MemoryBackend.php
+++ b/core/lib/Drupal/Core/Cache/MemoryBackend.php
@@ -26,17 +26,20 @@ class MemoryBackend implements CacheBackendInterface {
   /**
    * The cache tag service.
    *
-   * @var \Drupal\Core\Cache\CacheTagInterface
+   * @var \Drupal\Core\Cache\CacheTagBackendInterface
    */
   protected $cacheTag;
 
   /**
    * Constructs a MemoryBackend object.
    *
+   *
+   * @param \Drupal\Core\Cache\CacheTagBackendInterface
+   *   The cache tag service.
    * @param string $bin
    *   The cache bin for which the object is created.
    */
-  public function __construct(CacheTagInterface $cache_tag, $bin) {
+  public function __construct(CacheTagBackendInterface $cache_tag, $bin) {
     $this->cacheTag = $cache_tag;
   }
 
@@ -92,6 +95,7 @@ protected function prepareItem($cache, $allow_invalid) {
 
     // Check expire time.
     $cache->valid = $time_valid = $cache->expire == Cache::PERMANENT || $cache->expire >= REQUEST_TIME;
+    $cache->tags = $this->cacheTag->raiseTags($cache->tags);
 
     $this->cacheTag->prepareGet($cache);
     if ($cache->deleted) {
diff --git a/core/lib/Drupal/Core/Cache/MemoryBackendFactory.php b/core/lib/Drupal/Core/Cache/MemoryBackendFactory.php
index 917110d..acaa82f 100644
--- a/core/lib/Drupal/Core/Cache/MemoryBackendFactory.php
+++ b/core/lib/Drupal/Core/Cache/MemoryBackendFactory.php
@@ -12,7 +12,7 @@ class MemoryBackendFactory implements CacheFactoryInterface {
   /**
    * The cache tag factory service.
    *
-   * @var \Drupal\Core\Cache\CacheTagFactory
+   * @var \Drupal\Core\Cache\CacheTagBackendFactory
    */
   protected $cacheTagFactory;
 
@@ -21,7 +21,7 @@ class MemoryBackendFactory implements CacheFactoryInterface {
    *
    * @param \Drupal\Core\Database\Connection $connection
    */
-  function __construct(CacheTagFactory $cache_tag_factory) {
+  function __construct(CacheTagBackendFactory $cache_tag_factory) {
     $this->cacheTagFactory = $cache_tag_factory;
   }
 
diff --git a/core/lib/Drupal/Core/Cache/MemoryTag.php b/core/lib/Drupal/Core/Cache/MemoryTag.php
deleted file mode 100644
index 26952c4..0000000
--- a/core/lib/Drupal/Core/Cache/MemoryTag.php
+++ /dev/null
@@ -1,96 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Cache\DatabaseTag.
- */
-
-namespace Drupal\Core\Cache;
-
-/**
- * Class DatabaseTag.
- */
-class MemoryTag extends CacheTagBase {
-  /**
-   * The cache tag storage.
-   *
-   * @var array
-   */
-  protected $storage = array();
-
-  /**
-   * Ensure there is an entry in storage array for a given tag.
-   *
-   * @param $tag string
-   *   Tag name.
-   */
-  protected function ensureItem($tag) {
-    if (empty($this->storage[$tag])) {
-      $this->storage[$tag] = array(
-        'invalidations' => 0,
-        'deletions' => 0,
-      );
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function invalidateTags(array $tags) {
-    foreach ($this->flattenTags($tags) as $tag) {
-      $this->ensureItem($tag);
-      $this->storage[$tag]['invalidations']++;
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function deleteTags(array $tags) {
-    foreach ($this->flattenTags($tags) as $tag) {
-      $this->ensureItem($tag);
-      $this->storage[$tag]['deletions']++;
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function checksumTags(array $tags, $set_context) {
-    $flat_tags = $this->flattenTags($tags);
-    $checksum = array(
-      'invalidations' => 0,
-      'deletions' => 0,
-    );
-
-    foreach ($flat_tags as $tag) {
-      $this->ensureItem($tag);
-      $checksum['invalidations'] += $this->storage[$tag]['invalidations'];
-      $checksum['deletions'] += $this->storage[$tag]['deletions'];
-    }
-
-    return $checksum;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function prepareGet(&$item) {
-    $checksum = $this->checksumTags($item->tags, FALSE);
-
-    // Check if deleteTags() has been called with any of the entry's tags.
-    $item->deleted = $item->checksum_deletions != $checksum['deletions'];
-
-    // Check if invalidateTags() has been called with any of the entry's tags.
-    if ($item->checksum_invalidations != $checksum['invalidations']) {
-      $item->valid = FALSE;
-    }
-  }
-
-  /**
-   * {@inheritdoc}.
-   */
-  public function clearCache() {
-    // Nothing to be done here.
-  }
-}
diff --git a/core/lib/Drupal/Core/Cache/MemoryTagBackend.php b/core/lib/Drupal/Core/Cache/MemoryTagBackend.php
new file mode 100644
index 0000000..d7dba4f
--- /dev/null
+++ b/core/lib/Drupal/Core/Cache/MemoryTagBackend.php
@@ -0,0 +1,96 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Cache\MemoryTagBackend.
+ */
+
+namespace Drupal\Core\Cache;
+
+/**
+ * Class MemoryTagBackend.
+ */
+class MemoryTagBackend extends CacheTagBackendBase {
+  /**
+   * The cache tag storage.
+   *
+   * @var array
+   */
+  protected $storage = array();
+
+  /**
+   * Ensure there is an entry in storage array for a given tag.
+   *
+   * @param $tag string
+   *   Tag name.
+   */
+  protected function ensureItem($tag) {
+    if (empty($this->storage[$tag])) {
+      $this->storage[$tag] = array(
+        'invalidations' => 0,
+        'deletions' => 0,
+      );
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function invalidateTags(array $tags) {
+    foreach ($this->flattenTags($tags) as $tag) {
+      $this->ensureItem($tag);
+      $this->storage[$tag]['invalidations']++;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteTags(array $tags) {
+    foreach ($this->flattenTags($tags) as $tag) {
+      $this->ensureItem($tag);
+      $this->storage[$tag]['deletions']++;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function checksumTags(array $tags, $set_context) {
+    $flat_tags = $this->flattenTags($tags);
+    $checksum = array(
+      'invalidations' => 0,
+      'deletions' => 0,
+    );
+
+    foreach ($flat_tags as $tag) {
+      $this->ensureItem($tag);
+      $checksum['invalidations'] += $this->storage[$tag]['invalidations'];
+      $checksum['deletions'] += $this->storage[$tag]['deletions'];
+    }
+
+    return $checksum;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function prepareGet(&$item) {
+    $checksum = $this->checksumTags($item->tags, FALSE);
+
+    // Check if deleteTags() has been called with any of the entry's tags.
+    $item->deleted = $item->checksum_deletions != $checksum['deletions'];
+
+    // Check if invalidateTags() has been called with any of the entry's tags.
+    if ($item->checksum_invalidations != $checksum['invalidations']) {
+      $item->valid = FALSE;
+    }
+  }
+
+  /**
+   * {@inheritdoc}.
+   */
+  public function clearCache() {
+    // Nothing to be done here.
+  }
+}
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index b03d826..a6afe92 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -1058,8 +1058,8 @@ protected function resetAll() {
   protected function refreshVariables() {
     // Clear the tag cache.
     $this->container->get('cache.tag.database')->clearCache();
-    drupal_static_reset('Drupal\Core\Cache\CacheTagInterface::tagCache');
-    drupal_static_reset('Drupal\Core\Cache\DatabaseTag::deletedTags');
+    drupal_static_reset('Drupal\Core\Cache\CacheTagBackendInterface::tagCache');
+    drupal_static_reset('Drupal\Core\Cache\DatabaseTagBackend::deletedTags');
 
     $this->container->get('config.factory')->reset();
     $this->container->get('state')->resetCache();
diff --git a/core/modules/system/lib/Drupal/system/Tests/Cache/BackendChainUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/Cache/BackendChainUnitTest.php
index c2207d5..dc97dc4 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Cache/BackendChainUnitTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Cache/BackendChainUnitTest.php
@@ -9,7 +9,7 @@
 
 use Drupal\Core\Cache\BackendChain;
 use Drupal\Core\Cache\MemoryBackend;
-use Drupal\Core\Cache\MemoryTag;
+use Drupal\Core\Cache\MemoryTagBackend;
 
 /**
  * Tests BackendChain using GenericCacheBackendUnitTestBase.
@@ -28,7 +28,7 @@ protected function createCacheBackend($bin) {
     $chain = new BackendChain($bin);
 
     // We need to create some various backends in the chain.
-    $cache_tag = new MemoryTag();
+    $cache_tag = new MemoryTagBackend();
     $chain
       ->appendBackend(new MemoryBackend($cache_tag, 'foo'))
       ->prependBackend(new MemoryBackend($cache_tag, 'bar'))
diff --git a/core/modules/system/lib/Drupal/system/Tests/Cache/MemoryBackendUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/Cache/MemoryBackendUnitTest.php
index 9ae5488..f6cf75c 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Cache/MemoryBackendUnitTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Cache/MemoryBackendUnitTest.php
@@ -8,7 +8,7 @@
 namespace Drupal\system\Tests\Cache;
 
 use Drupal\Core\Cache\MemoryBackend;
-use Drupal\Core\Cache\MemoryTag;
+use Drupal\Core\Cache\MemoryTagBackend;
 
 /**
  * Tests MemoryBackend using GenericCacheBackendUnitTestBase.
@@ -30,6 +30,6 @@ public static function getInfo() {
    *   A new MemoryBackend object.
    */
   protected function createCacheBackend($bin) {
-    return new MemoryBackend(new MemoryTag(), $bin);
+    return new MemoryBackend(new MemoryTagBackend(), $bin);
   }
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Plugin/CacheDecoratorTest.php b/core/modules/system/lib/Drupal/system/Tests/Plugin/CacheDecoratorTest.php
index 2deb327..75fe0a6 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Plugin/CacheDecoratorTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Plugin/CacheDecoratorTest.php
@@ -7,9 +7,8 @@
 
 namespace Drupal\system\Tests\Plugin;
 
-use Drupal\Core\Cache\MemoryBackendFactory;
 use Drupal\Core\Cache\MemoryBackend;
-use Drupal\Core\Cache\MemoryTag;
+use Drupal\Core\Cache\MemoryTagBackend;
 use Drupal\system\Tests\Plugin\Discovery\DiscoveryTestBase;
 use Drupal\Component\Plugin\Discovery\StaticDiscovery;
 use Drupal\Core\Plugin\Discovery\CacheDecorator;
@@ -48,7 +47,7 @@ public function setUp() {
     // Use a non-db cache backend, so that we can use DiscoveryTestBase (which
     // extends UnitTestBase).
     // @todo switch to injecting the MemoryBackend http://drupal.org/node/1903346
-    \Drupal::getContainer()->set("cache.$this->cacheBin", new MemoryBackend(new MemoryTag(), $this->cacheBin));
+    \Drupal::getContainer()->set("cache.$this->cacheBin", new MemoryBackend(new MemoryTagBackend(), $this->cacheBin));
 
     // Create discovery objects to test.
     $this->emptyDiscovery = new StaticDiscovery();
diff --git a/core/tests/Drupal/Tests/Core/Cache/BackendChainImplementationUnitTest.php b/core/tests/Drupal/Tests/Core/Cache/BackendChainImplementationUnitTest.php
index 8841720..7b36ce9 100644
--- a/core/tests/Drupal/Tests/Core/Cache/BackendChainImplementationUnitTest.php
+++ b/core/tests/Drupal/Tests/Core/Cache/BackendChainImplementationUnitTest.php
@@ -10,7 +10,7 @@
 use Drupal\Core\Cache\BackendChain;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\MemoryBackend;
-use Drupal\Core\Cache\MemoryTag;
+use Drupal\Core\Cache\MemoryTagBackend;
 use Drupal\Tests\UnitTestCase;
 
 /**
@@ -60,7 +60,7 @@ public function setUp() {
     parent::setUp();
 
     // Set up three memory backends to be used in the chain.
-    $cache_tag = new MemoryTag();
+    $cache_tag = new MemoryTagBackend();
     $this->firstBackend = new MemoryBackend($cache_tag, 'foo');
     $this->secondBackend = new MemoryBackend($cache_tag, 'bar');
     $this->thirdBackend = new MemoryBackend($cache_tag, 'baz');
diff --git a/core/tests/Drupal/Tests/Core/Cache/CacheCollectorTest.php b/core/tests/Drupal/Tests/Core/Cache/CacheCollectorTest.php
index 7740523..0b85e6d 100644
--- a/core/tests/Drupal/Tests/Core/Cache/CacheCollectorTest.php
+++ b/core/tests/Drupal/Tests/Core/Cache/CacheCollectorTest.php
@@ -29,7 +29,7 @@ class CacheCollectorTest extends UnitTestCase {
   /**
    * The cache tag backend to use.
    *
-   * @var \Drupal\Core\Cache\CacheTagInterface|\PHPUnit_Framework_MockObject_MockObject
+   * @var \Drupal\Core\Cache\CacheTagBackendInterface|\PHPUnit_Framework_MockObject_MockObject
    */
   protected $cacheTag;
 
@@ -67,7 +67,7 @@ public static function getInfo() {
    */
   protected function setUp() {
     $this->cache = $this->getMock('Drupal\Core\Cache\CacheBackendInterface');
-    $this->cacheTag = $this->getMock('Drupal\Core\Cache\CacheTagInterface');
+    $this->cacheTag = $this->getMock('Drupal\Core\Cache\CacheTagBackendInterface');
     $this->lock = $this->getMock('Drupal\Core\Lock\LockBackendInterface');
     $this->cid = $this->randomName();
     $this->collector = new CacheCollectorHelper($this->cid, $this->cache, $this->lock);
diff --git a/core/tests/Drupal/Tests/Core/Config/CachedStorageTest.php b/core/tests/Drupal/Tests/Core/Config/CachedStorageTest.php
index 81a6248..a742bf7 100644
--- a/core/tests/Drupal/Tests/Core/Config/CachedStorageTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/CachedStorageTest.php
@@ -2,12 +2,11 @@
 
 namespace Drupal\Tests\Core\Config;
 
-use Drupal\Core\Cache\MemoryTag;
+use Drupal\Core\Cache\MemoryTagBackend;
 use Drupal\Tests\UnitTestCase;
 use Drupal\Core\Config\CachedStorage;
 use Drupal\Core\Cache\MemoryBackend;
 use Drupal\Core\Cache\NullBackend;
-use Drupal\Core\Cache\CacheBackendInterface;
 
 /**
  * Tests the interaction of cache and file storage in CachedStorage.
@@ -52,7 +51,7 @@ public function testListAllPrimedPersistentCache() {
     $storage->expects($this->never())->method('listAll');
 
     $response = array("$prefix." . $this->randomName(), "$prefix." . $this->randomName());
-    $cache = new MemoryBackend(new MemoryTag(), __FUNCTION__);
+    $cache = new MemoryBackend(new MemoryTagBackend(), __FUNCTION__);
     $cache->set('find:' . $prefix, $response);
     $cachedStorage = new CachedStorage($storage, $cache);
     $this->assertEquals($response, $cachedStorage->listAll($prefix));
@@ -76,7 +75,7 @@ public function testGetMultipleOnPrimedCache() {
     );
     $storage = $this->getMock('Drupal\Core\Config\StorageInterface');
     $storage->expects($this->never())->method('readMultiple');
-    $cache = new MemoryBackend(new MemoryTag(), __FUNCTION__);
+    $cache = new MemoryBackend(new MemoryTagBackend(), __FUNCTION__);
     foreach ($configCacheValues as $key => $value) {
       $cache->set($key, $value);
     }
@@ -103,7 +102,7 @@ public function testGetMultipleOnPartiallyPrimedCache() {
         'foo' => 'bar',
       ),
     );
-    $cache = new MemoryBackend(new MemoryTag(), __FUNCTION__);
+    $cache = new MemoryBackend(new MemoryTagBackend(), __FUNCTION__);
     foreach ($configCacheValues as $key => $value) {
       $cache->set($key, $value);
     }
@@ -138,7 +137,7 @@ public function testGetMultipleOnPartiallyPrimedCache() {
    */
   public function testReadNonExistentFileCacheMiss() {
     $name = 'config.does_not_exist';
-    $cache = new MemoryBackend(new MemoryTag(), __FUNCTION__);
+    $cache = new MemoryBackend(new MemoryTagBackend(), __FUNCTION__);
     $storage = $this->getMock('Drupal\Core\Config\StorageInterface');
     $storage->expects($this->once())
             ->method('read')
@@ -158,7 +157,7 @@ public function testReadNonExistentFileCacheMiss() {
    */
   public function testReadNonExistentFileCached() {
     $name = 'config.does_not_exist';
-    $cache = new MemoryBackend(new MemoryTag(), __FUNCTION__);
+    $cache = new MemoryBackend(new MemoryTagBackend(), __FUNCTION__);
     $cache->set($name, FALSE);
 
     $storage = $this->getMock('Drupal\Core\Config\StorageInterface');
diff --git a/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php b/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php
index 7ea1e3b..2c109dd 100644
--- a/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php
@@ -68,7 +68,7 @@ class EntityManagerTest extends UnitTestCase {
   /**
    * The cache tag backend to use.
    *
-   * @var \Drupal\Core\Cache\CacheTagInterface|\PHPUnit_Framework_MockObject_MockObject
+   * @var \Drupal\Core\Cache\CacheTagBackendInterface|\PHPUnit_Framework_MockObject_MockObject
    */
   protected $cacheTag;
 
@@ -118,7 +118,7 @@ protected function setUp() {
 
     $this->cache = $this->getMock('Drupal\Core\Cache\CacheBackendInterface');
 
-    $this->cacheTag = $this->getMock('Drupal\Core\Cache\CacheTagInterface');
+    $this->cacheTag = $this->getMock('Drupal\Core\Cache\CacheTagBackendInterface');
 
     $this->languageManager = $this->getMockBuilder('Drupal\Core\Language\LanguageManager')
       ->disableOriginalConstructor()
diff --git a/core/tests/Drupal/Tests/Core/Extension/ThemeHandlerTest.php b/core/tests/Drupal/Tests/Core/Extension/ThemeHandlerTest.php
index e2816db..277bb1c 100644
--- a/core/tests/Drupal/Tests/Core/Extension/ThemeHandlerTest.php
+++ b/core/tests/Drupal/Tests/Core/Extension/ThemeHandlerTest.php
@@ -46,7 +46,7 @@ class ThemeHandlerTest extends UnitTestCase {
   /**
    * The mocked cache tag service.
    *
-   * @var \Drupal\Core\Cache\CacheTagInterface|\PHPUnit_Framework_MockObject_MockObject
+   * @var \Drupal\Core\Cache\CacheTagBackendInterface|\PHPUnit_Framework_MockObject_MockObject
    */
   protected $cacheTag;
 
@@ -103,7 +103,7 @@ protected function setUp() {
     $this->configFactory = $this->getConfigFactoryStub(array('system.theme' => array(), 'system.theme.disabled' => array()));
     $this->moduleHandler = $this->getMock('Drupal\Core\Extension\ModuleHandlerInterface');
     $this->cacheBackend = $this->getMock('Drupal\Core\Cache\CacheBackendInterface');
-    $this->cacheTag = $this->getMock('Drupal\Core\Cache\CacheTagInterface');
+    $this->cacheTag = $this->getMock('Drupal\Core\Cache\CacheTagBackendInterface');
     $this->infoParser = $this->getMock('Drupal\Core\Extension\InfoParserInterface');
     $this->configInstaller = $this->getMock('Drupal\Core\Config\ConfigInstallerInterface');
     $this->routeBuilder = $this->getMockBuilder('Drupal\Core\Routing\RouteBuilder')
diff --git a/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php b/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
index cf4692e..0cecfe9 100644
--- a/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php
@@ -161,7 +161,7 @@ public function testDefaultPluginManagerWithFilledCache() {
    */
   public function testCacheClearWithTags() {
     $cid = $this->randomName();
-    $memory_tag = $this->getMockBuilder('Drupal\Core\Cache\MemoryTag')
+    $memory_tag = $this->getMockBuilder('Drupal\Core\Cache\MemoryTagBackend')
       ->disableOriginalConstructor()
       ->getMock();
     $memory_tag
diff --git a/core/tests/Drupal/Tests/UnitTestCase.php b/core/tests/Drupal/Tests/UnitTestCase.php
index ba1b821..9de71a1 100644
--- a/core/tests/Drupal/Tests/UnitTestCase.php
+++ b/core/tests/Drupal/Tests/UnitTestCase.php
@@ -9,8 +9,7 @@
 
 use Drupal\Component\Utility\Random;
 use Drupal\Component\Utility\String;
-use Drupal\Core\Cache\CacheBackendInterface;
-use Drupal\Core\Cache\CacheTagInterface;
+use Drupal\Core\Cache\CacheTagBackendInterface;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 
 /**
@@ -199,13 +198,13 @@ public function getStringTranslationStub() {
   /**
    * Sets up a container with cache bins.
    *
-   * @param \Drupal\Core\Cache\CacheTagInterface $backend
+   * @param \Drupal\Core\Cache\CacheTagBackendInterface $backend
    *   The cache tag to set up.
    *
    * @return \Symfony\Component\DependencyInjection\ContainerInterface|\PHPUnit_Framework_MockObject_MockObject
    *   The container with the cache bins set up.
    */
-  protected function getContainerWithCacheTags(CacheTagInterface $backend) {
+  protected function getContainerWithCacheTags(CacheTagBackendInterface $backend) {
     $container = $this->getMock('Symfony\Component\DependencyInjection\ContainerInterface');
     $container->expects($this->any())
       ->method('getParameter')