diff --git a/core/core.services.yml b/core/core.services.yml
index b342ef7878..aef6c11af6 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -539,8 +539,8 @@ services:
     # @todo Remove this tag in https://www.drupal.org/node/2549143.
     tags:
       - { name: plugin_manager_cache_clear }
-  entity.static_cache:
-    class: Drupal\Core\Cache\StaticCache\StaticCache
+  entity.memory_cache:
+    class: Drupal\Core\Cache\MemoryCache\MemoryCache
   entity_type.manager:
     class: Drupal\Core\Entity\EntityTypeManager
     arguments: ['@container.namespaces', '@module_handler', '@cache.discovery', '@string_translation', '@class_resolver']
diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php
index 9d9eb10203..1cc067fc9b 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php
@@ -3,7 +3,7 @@
 namespace Drupal\Core\Config\Entity;
 
 use Drupal\Core\Cache\CacheableMetadata;
-use Drupal\Core\Cache\StaticCache\StaticCacheInterface;
+use Drupal\Core\Cache\MemoryCache\MemoryCacheInterface;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Config\ConfigImporterException;
 use Drupal\Core\Entity\EntityInterface;
@@ -105,13 +105,11 @@ class ConfigEntityStorage extends EntityStorageBase implements ConfigEntityStora
    *   The UUID service.
    * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
    *   The language manager.
-   * @param \Drupal\Core\Cache\StaticCache\StaticCacheInterface $static_cache
+   * @param \Drupal\Core\Cache\MemoryCache\MemoryCacheInterface|null $memory_cache
    *   The static cache backend.
    */
-  public function __construct(EntityTypeInterface $entity_type, ConfigFactoryInterface $config_factory, UuidInterface $uuid_service, LanguageManagerInterface $language_manager, StaticCacheInterface $static_cache = NULL) {
-    // @todo Remove this line in Drupal 9.0.x and make $static_cache required.
-    $static_cache = isset($static_cache) ? $static_cache : \Drupal::service('entity.static_cache');
-    parent::__construct($entity_type, $static_cache);
+  public function __construct(EntityTypeInterface $entity_type, ConfigFactoryInterface $config_factory, UuidInterface $uuid_service, LanguageManagerInterface $language_manager, MemoryCacheInterface $memory_cache = NULL) {
+    parent::__construct($entity_type, $memory_cache);
 
     $this->configFactory = $config_factory;
     $this->uuidService = $uuid_service;
@@ -127,7 +125,7 @@ public static function createInstance(ContainerInterface $container, EntityTypeI
       $container->get('config.factory'),
       $container->get('uuid'),
       $container->get('language_manager'),
-      $container->get('entity.static_cache')
+      $container->get('entity.memory_cache')
     );
   }
 
diff --git a/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php b/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php
index f58b3eb30c..53629ba600 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php
@@ -4,7 +4,7 @@
 
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\CacheBackendInterface;
-use Drupal\Core\Cache\StaticCache\StaticCacheInterface;
+use Drupal\Core\Cache\MemoryCache\MemoryCacheInterface;
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\Core\TypedData\TranslationStatusInterface;
@@ -45,13 +45,11 @@
    *   The entity manager.
    * @param \Drupal\Core\Cache\CacheBackendInterface $cache
    *   The cache backend to be used.
-   * @param \Drupal\Core\Cache\StaticCache\StaticCacheInterface $static_cache
+   * @param \Drupal\Core\Cache\MemoryCache\MemoryCacheInterface|null $memory_cache
    *   The static cache backend.
    */
-  public function __construct(EntityTypeInterface $entity_type, EntityManagerInterface $entity_manager, CacheBackendInterface $cache, StaticCacheInterface $static_cache = NULL) {
-    // @todo Remove this line in Drupal 9.0.x and make $static_cache required.
-    $static_cache = isset($static_cache) ? $static_cache : \Drupal::service('entity.static_cache');
-    parent::__construct($entity_type, $static_cache);
+  public function __construct(EntityTypeInterface $entity_type, EntityManagerInterface $entity_manager, CacheBackendInterface $cache, MemoryCacheInterface $memory_cache = NULL) {
+    parent::__construct($entity_type, $memory_cache);
     $this->bundleKey = $this->entityType->getKey('bundle');
     $this->entityManager = $entity_manager;
     $this->cacheBackend = $cache;
@@ -65,7 +63,7 @@ public static function createInstance(ContainerInterface $container, EntityTypeI
       $entity_type,
       $container->get('entity.manager'),
       $container->get('cache.entity'),
-      $container->get('entity.static_cache')
+      $container->get('entity.memory_cache')
     );
   }
 
@@ -984,7 +982,7 @@ public function loadUnchanged($id) {
         // As we've removed the entity from the static cache already we have to
         // put the loaded unchanged entity there to simulate the behavior of the
         // parent.
-        $this->setStaticCache($entities);
+        $this->setMemoryCache($entities);
       }
     }
 
diff --git a/core/lib/Drupal/Core/Entity/EntityStorageBase.php b/core/lib/Drupal/Core/Entity/EntityStorageBase.php
index 8c790bdb44..b3888b744c 100644
--- a/core/lib/Drupal/Core/Entity/EntityStorageBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityStorageBase.php
@@ -3,20 +3,13 @@
 namespace Drupal\Core\Entity;
 
 use Drupal\Core\Entity\Query\QueryInterface;
-use Drupal\Core\Cache\StaticCache\StaticCacheInterface;
+use Drupal\Core\Cache\MemoryCache\MemoryCacheInterface;
 
 /**
  * A base entity storage class.
  */
 abstract class EntityStorageBase extends EntityHandlerBase implements EntityStorageInterface, EntityHandlerInterface {
 
-  /**
-   * Static cache of entities, keyed by entity ID.
-   *
-   * @var array
-   */
-  protected $entities = [];
-
   /**
    * Entity type ID for this storage.
    *
@@ -76,9 +69,9 @@
   /**
    * The static cache.
    *
-   * @var \Drupal\Core\Cache\StaticCache\StaticCacheInterface
+   * @var \Drupal\Core\Cache\MemoryCache\MemoryCacheInterface
    */
-  protected $staticCache;
+  protected $memoryCache;
 
   /**
    * The static cache cache tag.
@@ -92,19 +85,19 @@
    *
    * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
    *   The entity type definition.
-   * @param \Drupal\Core\Cache\StaticCache\StaticCacheInterface
+   * @param \Drupal\Core\Cache\MemoryCache\MemoryCacheInterface|null
    *   The static cache.
    */
-  public function __construct(EntityTypeInterface $entity_type, StaticCacheInterface $static_cache = NULL) {
+  public function __construct(EntityTypeInterface $entity_type, MemoryCacheInterface $memory_cache = NULL) {
     $this->entityTypeId = $entity_type->id();
     $this->entityType = $entity_type;
     $this->idKey = $this->entityType->getKey('id');
     $this->uuidKey = $this->entityType->getKey('uuid');
     $this->langcodeKey = $this->entityType->getKey('langcode');
     $this->entityClass = $this->entityType->getClass();
-    // @todo Remove this line in Drupal 9.0.x and make $static_cache required.
-    $this->staticCache = isset($static_cache) ? $static_cache : \Drupal::service('entity.static_cache');
-    $this->cacheTag = 'entity_static_cache:' . $this->entityTypeId;
+    // @todo Remove this line in Drupal 9.0.x and make $memory_cache required.
+    $this->memoryCache = isset($memory_cache) ? $memory_cache : \Drupal::service('entity.memory_cache');
+    $this->cacheTag = 'entity.memory_cache:' . $this->entityTypeId;
   }
 
   /**
@@ -142,12 +135,12 @@ public function loadUnchanged($id) {
   public function resetCache(array $ids = NULL) {
     if ($this->entityType->isStaticallyCacheable() && isset($ids)) {
       foreach ($ids as $id) {
-        $this->staticCache->delete($this->getCacheId($id));
+        $this->memoryCache->delete($this->getCacheId($id));
       }
     }
     else {
       // Call the backend method directly.
-      $this->staticCache->invalidateTags([$this->cacheTag]);
+      $this->memoryCache->invalidateTags([$this->cacheTag]);
     }
   }
 
@@ -160,12 +153,12 @@ public function resetCache(array $ids = NULL) {
    * @return \Drupal\Core\Entity\EntityInterface[]
    *   Array of entities from the entity cache.
    */
-  protected function getFromStaticCache(array $ids) {
+  protected function getFromMemoryCache(array $ids) {
     $entities = [];
     // Load any available entities from the internal cache.
     if ($this->entityType->isStaticallyCacheable()) {
       foreach ($ids as $id) {
-        if ($cached = $this->staticCache->get($this->getCacheId($id))) {
+        if ($cached = $this->memoryCache->get($this->getCacheId($id))) {
           $entities[$id] = $cached->data;
         }
       }
@@ -179,10 +172,10 @@ protected function getFromStaticCache(array $ids) {
    * @param \Drupal\Core\Entity\EntityInterface[] $entities
    *   Entities to store in the cache.
    */
-  protected function setStaticCache(array $entities) {
+  protected function setMemoryCache(array $entities) {
     if ($this->entityType->isStaticallyCacheable()) {
       foreach ($entities as $id => $entity) {
-        $this->staticCache->set($this->getCacheId($entity->id()), $entity, StaticCacheInterface::CACHE_PERMANENT, [$this->cacheTag]);
+        $this->memoryCache->set($this->getCacheId($entity->id()), $entity, MemoryCacheInterface::CACHE_PERMANENT, [$this->cacheTag]);
       }
     }
   }
@@ -262,7 +255,7 @@ public function loadMultiple(array $ids = NULL) {
     // Try to load entities from the static cache, if the entity type supports
     // static caching.
     if ($this->entityType->isStaticallyCacheable() && $ids) {
-      $entities += $this->getFromStaticCache($ids);
+      $entities += $this->getFromMemoryCache($ids);
       // If any entities were loaded, remove them from the ids still to load.
       if ($passed_ids) {
         $ids = array_keys(array_diff_key($passed_ids, $entities));
@@ -287,7 +280,7 @@ public function loadMultiple(array $ids = NULL) {
     if ($this->entityType->isStaticallyCacheable()) {
       // Add entities to the cache.
       if (!empty($queried_entities)) {
-        $this->setStaticCache($queried_entities);
+        $this->setMemoryCache($queried_entities);
       }
     }
 
@@ -575,16 +568,4 @@ public function getAggregateQuery($conjunction = 'AND') {
    */
   abstract protected function getQueryServiceName();
 
-  /**
-   * {@inheritdoc}
-   */
-  public function __sleep() {
-    // In case the storage is being serialized then we prevent from serializing
-    // the static cache of entities together with it, as this could lead to a
-    // memory leak.
-    $vars = parent::__sleep();
-    unset($vars['entities']);
-    return $vars;
-  }
-
 }
diff --git a/core/lib/Drupal/Core/Entity/KeyValueStore/KeyValueEntityStorage.php b/core/lib/Drupal/Core/Entity/KeyValueStore/KeyValueEntityStorage.php
index 7c8d30163b..3898a9e74c 100644
--- a/core/lib/Drupal/Core/Entity/KeyValueStore/KeyValueEntityStorage.php
+++ b/core/lib/Drupal/Core/Entity/KeyValueStore/KeyValueEntityStorage.php
@@ -83,7 +83,7 @@ public static function createInstance(ContainerInterface $container, EntityTypeI
       $container->get('keyvalue')->get('entity_storage__' . $entity_type->id()),
       $container->get('uuid'),
       $container->get('language_manager'),
-      $container->get('entity.static_cache')
+      $container->get('entity.memory_cache')
     );
   }
 
diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
index 7768e01e10..2bbd089ce0 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
@@ -133,7 +133,7 @@ public static function createInstance(ContainerInterface $container, EntityTypeI
       $container->get('entity.manager'),
       $container->get('cache.entity'),
       $container->get('language_manager'),
-      $container->get('entity.static_cache')
+      $container->get('entity.memory_cache')
     );
   }
 
@@ -161,13 +161,11 @@ public function getFieldStorageDefinitions() {
    *   The cache backend to be used.
    * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
    *   The language manager.
-   * @param \Drupal\Core\Cache\CacheBackendInterface $static_cache
-   *   The static cache backend to be used.
+   * @param \Drupal\Core\Cache\MemoryCache\MemoryCacheInterface|null $memory_cache
+   *   The memory cache backend to be used.
    */
-  public function __construct(EntityTypeInterface $entity_type, Connection $database, EntityManagerInterface $entity_manager, CacheBackendInterface $cache, LanguageManagerInterface $language_manager, CacheBackendInterface $static_cache = NULL) {
-    // @todo Remove this line in Drupal 9.0.x and make $static_cache required.
-    $static_cache = isset($static_cache) ? $static_cache : \Drupal::service('entity.static_cache');
-    parent::__construct($entity_type, $entity_manager, $cache, $static_cache);
+  public function __construct(EntityTypeInterface $entity_type, Connection $database, EntityManagerInterface $entity_manager, CacheBackendInterface $cache, LanguageManagerInterface $language_manager, CacheBackendInterface $memory_cache = NULL) {
+    parent::__construct($entity_type, $entity_manager, $cache, $memory_cache);
     $this->database = $database;
     $this->languageManager = $language_manager;
     $this->initTableLayout();
diff --git a/core/lib/Drupal/Core/MemoryCache/MemoryCache.php b/core/lib/Drupal/Core/MemoryCache/MemoryCache.php
index fa61227f15..b0d2ff502a 100644
--- a/core/lib/Drupal/Core/MemoryCache/MemoryCache.php
+++ b/core/lib/Drupal/Core/MemoryCache/MemoryCache.php
@@ -1,18 +1,18 @@
 <?php
 
-namespace Drupal\Core\Cache\StaticCache;
+namespace Drupal\Core\Cache\MemoryCache;
 
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\MemoryBackend;
 
 /**
- * Defines a static cache implementation.
+ * Defines a memory cache implementation.
  *
  * Stores cache items in memory using a PHP array.
  *
  * @ingroup cache
  */
-class StaticCache extends MemoryBackend implements StaticCacheInterface {
+class MemoryCache extends MemoryBackend implements MemoryCacheInterface {
 
   /**
    * Prepares a cached item.
@@ -49,6 +49,8 @@ protected function prepareItem($cache, $allow_invalid) {
    */
   public function set($cid, $data, $expire = Cache::PERMANENT, array $tags = []) {
     assert('\Drupal\Component\Assertion\Inspector::assertAllStrings($tags)', 'Cache Tags must be strings.');
+   $tags = array_unique($tags);
+
     $this->cache[$cid] = (object) [
       'cid' => $cid,
       'data' => $data,
diff --git a/core/modules/config/tests/config_entity_static_cache_test/src/ConfigOverrider.php b/core/modules/config/tests/config_entity_static_cache_test/src/ConfigOverrider.php
index 9d48e0b1b9..4e6a490f84 100644
--- a/core/modules/config/tests/config_entity_static_cache_test/src/ConfigOverrider.php
+++ b/core/modules/config/tests/config_entity_static_cache_test/src/ConfigOverrider.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\config_entity_static_cache_test;
+namespace Drupal\config_entity.memory_cache_test;
 
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Config\ConfigFactoryOverrideInterface;
@@ -26,7 +26,7 @@ public function loadOverrides($names) {
    * {@inheritdoc}
    */
   public function getCacheSuffix() {
-    return 'config_entity_static_cache_test';
+    return 'config_entity.memory_cache_test';
   }
 
   /**
diff --git a/core/modules/user/tests/src/Functional/Update/UserUpdateOrderPermissionsTest.php b/core/modules/user/tests/src/Functional/Update/UserUpdateOrderPermissionsTest.php
index accca3c2b7..5129321162 100644
--- a/core/modules/user/tests/src/Functional/Update/UserUpdateOrderPermissionsTest.php
+++ b/core/modules/user/tests/src/Functional/Update/UserUpdateOrderPermissionsTest.php
@@ -31,7 +31,7 @@ public function testPermissionsOrder() {
     $this->assertNotIdentical($permissions, $authenticated->getPermissions());
 
     $this->runUpdates();
-    \Drupal::service('entity.static_cache')->reset();
+    \Drupal::service('entity.memory_cache')->reset();
     $authenticated = Role::load('authenticated');
     $this->assertIdentical($permissions, $authenticated->getPermissions());
   }
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityStaticCacheTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityStaticCacheTest.php
index 1cd9cb1753..c8475342ff 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityStaticCacheTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityStaticCacheTest.php
@@ -2,7 +2,7 @@
 
 namespace Drupal\KernelTests\Core\Config;
 
-use Drupal\config_entity_static_cache_test\ConfigOverrider;
+use Drupal\config_entity.memory_cache_test\ConfigOverrider;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
@@ -17,7 +17,7 @@ class ConfigEntityStaticCacheTest extends KernelTestBase {
    *
    * @var array
    */
-  public static $modules = ['config_test', 'config_entity_static_cache_test'];
+  public static $modules = ['config_test', 'config_entity.memory_cache_test'];
 
   /**
    * The type ID of the entity under test.
@@ -54,7 +54,7 @@ public function testCacheHit() {
       ->getStorage($this->entityTypeId);
     $entity_1 = $storage->load($this->entityId);
     $entity_2 = $storage->load($this->entityId);
-    // config_entity_static_cache_test_config_test_load() sets _loadStamp to a
+    // config_entity.memory_cache_test_config_test_load() sets _loadStamp to a
     // random string. If they match, it means $entity_2 was retrieved from the
     // static cache rather than going through a separate load sequence.
     $this->assertSame($entity_1->_loadStamp, $entity_2->_loadStamp);