diff --git a/core/lib/Drupal/Core/Cache/ApcuBackend.php b/core/lib/Drupal/Core/Cache/ApcuBackend.php
index f6de468..40ede29 100644
--- a/core/lib/Drupal/Core/Cache/ApcuBackend.php
+++ b/core/lib/Drupal/Core/Cache/ApcuBackend.php
@@ -36,20 +36,29 @@ class ApcuBackend implements CacheBackendInterface {
   protected $binPrefix;
 
   /**
-   * Prefix for keys holding cache tags.
+   * Prefix for keys holding invalidation cache tags.
    *
    * Includes the site-specific prefix in $sitePrefix.
    *
    * @var string
    */
-  protected $tagsPrefix;
+  protected $invalidationsTagsPrefix;
+
+  /**
+   * Prefix for keys holding invalidation cache tags.
+   *
+   * Includes the site-specific prefix in $sitePrefix.
+   *
+   * @var string
+   */
+  protected $deletionsTagsPrefix;
 
   /**
    * A static cache of all tags checked during the request.
    *
    * @var array
    */
-  protected static $tagCache = array();
+  protected static $tagCache = array('deletions' => array(), 'invalidations' => array());
 
   /**
    * Constructs a new ApcuBackend instance.
@@ -63,7 +72,8 @@ public function __construct($bin, $site_prefix) {
     $this->bin = $bin;
     $this->sitePrefix = $site_prefix;
     $this->binPrefix = $this->sitePrefix . '::' . $this->bin . '::';
-    $this->tagsPrefix = $this->sitePrefix . '::tags::';
+    $this->invalidationsTagsPrefix = $this->sitePrefix . '::itags::';
+    $this->deletionsTagsPrefix = $this->sitePrefix . '::dtags::';
   }
 
   /**
@@ -153,16 +163,16 @@ protected function prepareItem($cache, $allow_invalid) {
     $cache->tags = $cache->tags ? explode(' ', $cache->tags) : array();
     $checksum = $this->checksumTags($cache->tags);
 
-    // The cache data is invalid if any of its tags have been cleared since.
-    if (!$this->validTags($checksum, $cache->tags)) {
+    // Check if deleteTags() has been called with any of the entry's tags.
+    if ($cache->checksum_deletions != $checksum['deletions']) {
       return FALSE;
     }
 
     // Check expire time.
-    $cache->valid = ($cache->expire == CacheBackendInterface::CACHE_PERMANENT) || ($cache->expire >= REQUEST_TIME);
+    $cache->valid = $cache->expire == Cache::PERMANENT || $cache->expire >= REQUEST_TIME;
 
     // Check if invalidateTags() has been called with any of the entry's tags.
-    if ($cache->checksum != $checksum) {
+    if ($cache->checksum_invalidations != $checksum['invalidations']) {
       $cache->valid = FALSE;
     }
 
@@ -182,8 +192,9 @@ public function set($cid, $data, $expire = CacheBackendInterface::CACHE_PERMANEN
     $cache->created = REQUEST_TIME;
     $cache->expire = $expire;
     $cache->tags = implode(' ', $this->flattenTags($tags));
-    $cache->checksum = $this->checksumTags($tags);
-
+    $checksum = $this->checksumTags($tags);
+    $cache->checksum_invalidations = $checksum['invalidations'];
+    $cache->checksum_deletions = $checksum['deletions'];
     // APC serializes/unserializes any structure itself.
     $cache->serialized = 0;
     $cache->data = $data;
@@ -199,7 +210,7 @@ public function set($cid, $data, $expire = CacheBackendInterface::CACHE_PERMANEN
   }
 
   /**
-   * {@inheritdoc
+   * {@inheritdoc}
    */
   public function setMultiple(array $items = array()) {
     foreach ($items as $cid => $item) {
@@ -241,7 +252,8 @@ public function garbageCollection() {
    */
   public function removeBin() {
     $this->deleteAll();
-    apc_delete(new \APCIterator('user', '/^' . preg_quote($this->tagsPrefix, '/') . '/'));
+    apc_delete(new \APCIterator('user', '/^' . preg_quote($this->deletionsTagsPrefix, '/') . '/'));
+    apc_delete(new \APCIterator('user', '/^' . preg_quote($this->invalidationsTagsPrefix, '/') . '/'));
   }
 
   /**
@@ -283,8 +295,10 @@ public function invalidateAll() {
    */
   public function deleteTags(array $tags) {
     foreach ($this->flattenTags($tags) as $tag) {
-      apc_delete($this->tagsPrefix . $tag);
-      unset(static::$tagCache[$tag]);
+      apc_inc($this->deletionsTagsPrefix . $tag, 1, $success);
+      if (!$success) {
+        apc_store($this->deletionsTagsPrefix . $tag, 1);
+      }
     }
   }
 
@@ -293,33 +307,14 @@ public function deleteTags(array $tags) {
    */
   public function invalidateTags(array $tags) {
     foreach ($this->flattenTags($tags) as $tag) {
-      unset(static::$tagCache[$tag]);
-      apc_inc($this->tagsPrefix . $tag, 1, $success);
+      apc_inc($this->invalidationsTagsPrefix . $tag, 1, $success);
       if (!$success) {
-        apc_store($this->tagsPrefix . $tag, 1);
+        apc_store($this->invalidationsTagsPrefix . $tag, 1);
       }
     }
   }
 
   /**
-   * Compares two checksums of tags.
-   *
-   * Used to determine whether to serve a cached item or treat it as
-   * invalidated.
-   *
-   * @param int $checksum
-   *   The initial checksum to compare against.
-   * @param array $tags
-   *   An array of tags to calculate a checksum for.
-   *
-   * @return bool
-   *   TRUE if the checksums match, FALSE otherwise.
-   */
-  protected function validTags($checksum, array $tags) {
-    return $checksum == $this->checksumTags($tags);
-  }
-
-  /**
    * Flattens a tags array into a numeric array suitable for string storage.
    *
    * @param array $tags
@@ -357,21 +352,26 @@ protected function flattenTags(array $tags) {
    *   Sum of all invalidations.
    */
   protected function checksumTags(array $tags) {
-    $checksum = 0;
-    $query_tags = array();
+    $checksum = array('invalidations' => 0, 'deletions' => 0);
+    $query_tags = array('invalidations' => array(), 'deletions' => array());
 
     foreach ($this->flattenTags($tags) as $tag) {
-      if (isset(static::$tagCache[$tag])) {
-        $checksum += static::$tagCache[$tag];
-      }
-      else {
-        $query_tags[] = $this->tagsPrefix . $tag;
+      foreach (array('deletions', 'invalidations') as $type) {
+        if (isset(static::$tagCache[$type][$tag])) {
+          $checksum[$type] += static::$tagCache[$type][$tag];
+        }
+        else {
+          $query_tags[$type][] = $this->{$type . 'TagsPrefix'} . $tag;
+        }
       }
     }
-    if ($query_tags) {
-      $result = apc_fetch($query_tags);
-      static::$tagCache = array_merge(static::$tagCache, $result);
-      $checksum += array_sum($result);
+
+    foreach (array('deletions', 'invalidations') as $type) {
+      if ($query_tags[$type]) {
+        $result = apc_fetch($query_tags[$type]);
+        static::$tagCache[$type] = array_merge(static::$tagCache[$type], $result);
+        $checksum[$type] += array_sum($result);
+      }
     }
 
     return $checksum;