diff --git a/core/lib/Drupal/Core/Cache/ApcuBackend.php b/core/lib/Drupal/Core/Cache/ApcuBackend.php
index 46a73b6..9bac79e 100644
--- a/core/lib/Drupal/Core/Cache/ApcuBackend.php
+++ b/core/lib/Drupal/Core/Cache/ApcuBackend.php
@@ -36,15 +36,6 @@ class ApcuBackend implements CacheBackendInterface {
   protected $binPrefix;
 
   /**
-   * Prefix for keys holding invalidation cache tags.
-   *
-   * Includes the site-specific prefix in $sitePrefix.
-   *
-   * @var string
-   */
-  protected $invalidationsTagsPrefix;
-
-  /**
    * The cache tags checksum provider.
    *
    * @var \Drupal\Core\Cache\CacheTagsChecksumInterface
@@ -52,13 +43,6 @@ class ApcuBackend implements CacheBackendInterface {
   protected $checksumProvider;
 
   /**
-   * A static cache of all tags checked during the request.
-   *
-   * @var array
-   */
-  protected static $tagCache = array();
-
-  /**
    * Constructs a new ApcuBackend instance.
    *
    * @param string $bin
@@ -73,7 +57,6 @@ public function __construct($bin, $site_prefix, CacheTagsChecksumInterface $chec
     $this->sitePrefix = $site_prefix;
     $this->checksumProvider = $checksum_provider;
     $this->binPrefix = $this->sitePrefix . '::' . $this->bin . '::';
-    $this->invalidationsTagsPrefix = $this->sitePrefix . '::itags::';
   }
 
   /**