diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index e94f8e1..ae0ecba 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -2480,11 +2480,23 @@ function drupal_container(Container $new_container = NULL, $rebuild = FALSE) {
     $container
       ->register('config.storage.staging', 'Drupal\Core\Config\FileStorage')
       ->addArgument(config_get_config_directory(CONFIG_STAGING_DIRECTORY));
+    $container
+      ->register('state.storage', 'Drupal\Core\KeyValueStore\DatabaseStorage')
+      ->addArgument('state');
   }
   return $container;
 }
 
 /**
+ * Returns the state storage service.
+ *
+ * @return Drupal\Core\KeyValueStore\KeyValueStoreInterface
+ */
+function state() {
+  return drupal_container()->get('state.storage');
+}
+
+/**
  * Returns the test prefix if this is an internal request from SimpleTest.
  *
  * @return
diff --git a/core/includes/common.inc b/core/includes/common.inc
index c9913a2..fc198f1 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -3168,7 +3168,9 @@ function drupal_pre_render_styles($elements) {
 function drupal_build_css_cache($css) {
   $data = '';
   $uri = '';
-  $map = variable_get('drupal_css_cache_files', array());
+  if (!$map = state()->get('drupal_css_cache_files')) {
+    $map = array();
+  }
   // Create a new array so that only the file names are used to create the hash.
   // This prevents new aggregates from being created unnecessarily.
   $css_data = array();
@@ -3236,7 +3238,7 @@ function drupal_build_css_cache($css) {
     }
     // Save the updated map.
     $map[$key] = $uri;
-    variable_set('drupal_css_cache_files', $map);
+    state()->set('drupal_css_cache_files', $map);
   }
   return $uri;
 }
@@ -3401,7 +3403,7 @@ function _drupal_load_stylesheet($matches) {
  * Deletes old cached CSS files.
  */
 function drupal_clear_css_cache() {
-  variable_del('drupal_css_cache_files');
+  state()->delete('drupal_css_cache_files');
   file_scan_directory('public://css', '/.*/', array('callback' => 'drupal_delete_file_if_stale'));
 }
 
@@ -4711,7 +4713,9 @@ function drupal_add_tabledrag($table_id, $action, $relationship, $group, $subgro
 function drupal_build_js_cache($files) {
   $contents = '';
   $uri = '';
-  $map = variable_get('drupal_js_cache_files', array());
+  if (!$map = state()->get('drupal_js_cache_files')) {
+    $map = array();
+  }
   // Create a new array so that only the file names are used to create the hash.
   // This prevents new aggregates from being created unnecessarily.
   $js_data = array();
@@ -4756,7 +4760,7 @@ function drupal_build_js_cache($files) {
       }
     }
     $map[$key] = $uri;
-    variable_set('drupal_js_cache_files', $map);
+    state()->set('drupal_js_cache_files', $map);
   }
   return $uri;
 }
diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 1b6c8a3..ca107cc 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -310,7 +310,9 @@ function install_begin_request(&$install_state) {
     $container->register('config.factory', 'Drupal\Core\Config\ConfigFactory')
       ->addArgument(new Reference('config.storage'))
       ->addArgument(new Reference('dispatcher'));
-
+    $container
+      ->register('state.storage', 'Drupal\Core\KeyValueStore\DatabaseStorage')
+      ->addArgument('state');
     drupal_container($container);
   }
 
diff --git a/core/includes/menu.inc b/core/includes/menu.inc
index 8574dbe..4aeda61 100644
--- a/core/includes/menu.inc
+++ b/core/includes/menu.inc
@@ -451,7 +451,7 @@ function menu_get_item($path = NULL, $router_item = NULL) {
   if (!isset($router_items[$path])) {
     // Rebuild if we know it's needed, or if the menu masks are missing which
     // occurs rarely, likely due to a race condition of multiple rebuilds.
-    if (variable_get('menu_rebuild_needed', FALSE) || !variable_get('menu_masks', array())) {
+    if (state()->get('menu_rebuild_needed') || !variable_get('menu_masks', array())) {
       menu_router_rebuild();
     }
     $original_map = arg(NULL, $path);
@@ -2666,7 +2666,7 @@ function menu_router_rebuild() {
     menu_cache_clear_all();
     _menu_clear_page_cache();
     // Indicate that the menu has been successfully rebuilt.
-    variable_del('menu_rebuild_needed');
+    state()->delete('menu_rebuild_needed');
   }
   catch (Exception $e) {
     $transaction->rollback();
diff --git a/core/includes/path.inc b/core/includes/path.inc
index 07aeee5..71c10a3 100644
--- a/core/includes/path.inc
+++ b/core/includes/path.inc
@@ -72,7 +72,7 @@ function drupal_lookup_path($action, $path = '', $langcode = NULL) {
 
   // Retrieve the path alias whitelist.
   if (!isset($cache['whitelist'])) {
-    $cache['whitelist'] = variable_get('path_alias_whitelist', NULL);
+    $cache['whitelist'] = state()->get('path_alias_whitelist');
     if (!isset($cache['whitelist'])) {
       $cache['whitelist'] = drupal_path_alias_whitelist_rebuild();
     }
@@ -391,7 +391,7 @@ function drupal_path_alias_whitelist_rebuild($source = NULL) {
   // When paths are inserted, only rebuild the whitelist if the system path
   // has a top level component which is not already in the whitelist.
   if (!empty($source)) {
-    $whitelist = variable_get('path_alias_whitelist', NULL);
+    $whitelist = state()->get('path_alias_whitelist');
     if (isset($whitelist[strtok($source, '/')])) {
       return $whitelist;
     }
@@ -404,7 +404,7 @@ function drupal_path_alias_whitelist_rebuild($source = NULL) {
   foreach ($result as $row) {
     $whitelist[$row->path] = TRUE;
   }
-  variable_set('path_alias_whitelist', $whitelist);
+  state()->set('path_alias_whitelist', $whitelist);
   return $whitelist;
 }
 
diff --git a/core/includes/update.inc b/core/includes/update.inc
index 9dd8456..c6d6569 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -130,6 +130,36 @@ function update_prepare_d8_bootstrap() {
     update_extra_requirements($requirements);
 
     if ($has_required_schema) {
+      if (!db_table_exists('keyvalue')) {
+        $specs = array(
+          'description' => 'Generic key-value storage table.',
+          'fields' => array(
+            'name' => array(
+              'description' => 'The key.',
+              'type' => 'varchar',
+              'length' => 128,
+              'not null' => TRUE,
+              'default' => '',
+            ),
+            'collection' => array(
+              'description' => 'The collection of the variable.',
+              'type' => 'varchar',
+              'length' => 128,
+              'not null' => TRUE,
+              'default' => '',
+            ),
+            'value' => array(
+              'description' => 'The value.',
+              'type' => 'blob',
+              'not null' => TRUE,
+              'size' => 'big',
+              'translatable' => TRUE,
+            ),
+          ),
+          'primary key' => array('collection', 'name'),
+        );
+        db_create_table('keyvalue', $specs);
+      }
       // Bootstrap variables so we can update theme while preparing the update
       // process.
       drupal_bootstrap(DRUPAL_BOOTSTRAP_VARIABLES);
diff --git a/core/lib/Drupal/Core/KeyValueStore/AbstractStorage.php b/core/lib/Drupal/Core/KeyValueStore/AbstractStorage.php
new file mode 100644
index 0000000..408b9a8
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/AbstractStorage.php
@@ -0,0 +1,54 @@
+<?php
+/**
+ * @file
+ * Contains KeyValueStore\Storage\AbstracteBackend.
+ */
+
+namespace Drupal\Core\KeyValueStore;
+
+abstract class AbstractStorage implements KeyValueStoreInterface {
+
+  /**
+   * @var string
+   */
+  protected $collection;
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::__construct().
+   */
+  public function __construct($collection, array $options = array()) {
+    $this->collection = $collection;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::getCollectionName().
+   */
+  public function getCollectionName() {
+    return $this->collection;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::get().
+   */
+  public function get($key) {
+    $values = $this->getMultiple(array($key));
+    return reset($values);
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::setMultiple().
+   */
+  public function setMultiple(array $data) {
+    foreach ($data as $key => $value) {
+      $this->set($key, $value);
+    }
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::delete().
+   */
+  public function delete($key) {
+    $this->deleteMultiple(array($key));
+  }
+
+}
diff --git a/core/lib/Drupal/Core/KeyValueStore/DatabaseStorage.php b/core/lib/Drupal/Core/KeyValueStore/DatabaseStorage.php
new file mode 100644
index 0000000..78b19b2
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/DatabaseStorage.php
@@ -0,0 +1,89 @@
+<?php
+
+/**
+ * @file
+ * Contains KeyValueStore\Storage\DatabaseBackend.
+ */
+
+namespace Drupal\Core\KeyValueStore;
+
+/**
+ * Defines a default key/value store implementation.
+ *
+ * This is Drupal's default key/value store implementation. It uses the database to store
+ * key/value data.
+ */
+class DatabaseStorage extends AbstractStorage {
+
+  /**
+   * Overrides KeyValueStore\Storage\AbstractStorage::__construct().
+   */
+  public function __construct($collection, array $options = array()) {
+    parent::__construct($collection, $options);
+    $this->table = isset($options['table']) ? $options['table'] : 'keyvalue';
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::getMultiple().
+   */
+  public function getMultiple(array $keys) {
+    try {
+      $result = db_query('SELECT name, value FROM {' . db_escape_table($this->table) . '} WHERE name IN (:keys) AND collection = :collection', array(':keys' => $keys, ':collection' => $this->collection))->fetchAllAssoc('name');
+      $values = array();
+      foreach ($keys as $key) {
+        if (isset($result[$key]) && ($value = unserialize($result[$key]->value))) {
+          $values[$key] = $value;
+        }
+      }
+      return $values;
+    }
+    catch (\Exception $e) {
+      // If the database is never going to be available, key/value requests should
+      // return FALSE in order to allow exception handling to occur.
+      return array();
+    }
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::getAll().
+   */
+  public function getAll() {
+    $result = db_query('SELECT name, value FROM {' . db_escape_table($this->table) . '} WHERE collection = :collection', array(':collection' => $this->collection));
+    $values = array();
+
+    foreach ($result as $item) {
+      if ($item) {
+        $values[$item->name] = unserialize($item->value);
+      }
+    }
+    return $values;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::set().
+   */
+  public function set($key, $value) {
+    db_merge($this->table)
+      ->key(array('name' => $key))
+      ->fields(array(
+        'collection' => $this->collection,
+        'value' => serialize($value),
+      ))
+      ->execute();
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::deleteMultiple().
+   */
+  public function deleteMultiple(array $keys) {
+    // Delete in chunks when a large array is passed.
+    do {
+      db_delete($this->table)
+        ->condition('name', array_splice($keys, 0, 1000))
+        ->condition('collection', $this->collection)
+        ->execute();
+    }
+    while (count($keys));
+  }
+
+}
diff --git a/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreInterface.php b/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreInterface.php
new file mode 100644
index 0000000..d4d7b6c
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreInterface.php
@@ -0,0 +1,98 @@
+<?php
+
+/**
+ * @file
+ * Contains KeyValueStore\Storage\StorageInterface.
+ */
+
+namespace Drupal\Core\KeyValueStore;
+
+
+/**
+ * Defines the interface for key/value store implementations.
+ */
+interface KeyValueStoreInterface {
+  /**
+   * Constructs a new key/value collection.
+   *
+   * @param string $collection
+   *   The collection for which the object is created.
+   * @param array $options
+   *   An associative array of options for the key/value storage collection.
+   */
+  public function __construct($collection, array $options = array());
+
+  /**
+   * Returns the name of this collection.
+   *
+   * @return string
+   *   The name of this collection.
+   */
+  public function getCollectionName();
+
+  /**
+   * Returns the stored value for a given key.
+   *
+   * @param $key
+   *   The key of the data to retrieve.
+   *
+   * @return mixed
+   *   The stored value, or FALSE if no value exists.
+   */
+  public function get($key);
+
+  /**
+   * Returns the stored key/value pairs for a given set of keys.
+   *
+   * @param array $keys
+   *   A list of keys to retrieve.
+   *
+   * @return array
+   *   An associative array of items successfully returned, indexed by key.
+   *   @todo What's returned for non-existing keys?
+   */
+  public function getMultiple(array $keys);
+
+  /**
+   * Returns all stored key/value pairs in the collection.
+   *
+   * @return array
+   *   An associative array containing all stored items in the collection.
+   */
+  public function getAll();
+
+  /**
+   * Saves a value for a given key.
+   *
+   * @param string $key
+   *   The key of the data to store.
+   * @param mixed $value
+   *   The data to store.
+   */
+  public function set($key, $value);
+
+  /**
+   * Saves key/value pairs.
+   *
+   * @param array $data
+   *   An associative array of key/value pairs.
+   */
+  public function setMultiple(array $data);
+
+  /**
+   * Deletes an item from the key/value store.
+   *
+   * @param string $key
+   *   The item name to delete.
+   */
+  public function delete($key);
+
+  /**
+   * Deletes multiple items from the key/value store.
+   *
+   * @param array $keys
+   *   A list of item names to delete.
+   */
+  public function deleteMultiple(array $keys);
+
+}
diff --git a/core/lib/Drupal/Core/KeyValueStore/MemoryStorage.php b/core/lib/Drupal/Core/KeyValueStore/MemoryStorage.php
new file mode 100644
index 0000000..b53722b
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/MemoryStorage.php
@@ -0,0 +1,97 @@
+<?php
+
+/**
+ * @file
+ * Contains KeyValueStore\Storage\MemoryStorage.
+ */
+
+namespace Drupal\Core\KeyValueStore;
+
+/**
+ * Defines a default key/value store implementation.
+ *
+ * For speed reasons, this class does not use the AbstractStorage generic
+ * implementation.
+ */
+class MemoryStorage implements KeyValueStoreInterface {
+
+  /**
+   * @var array
+   */
+  protected $data = array();
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::__construct().
+   */
+  public function __construct($collection, array $options = array()) {
+    $this->collection = $collection;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::getCollectionName().
+   */
+  public function getCollectionName() {
+    return $this->collection;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::get().
+   */
+  public function get($key) {
+    return isset($this->data[$key]) ? $this->data[$key] : FALSE;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::getMultiple().
+   */
+  public function getMultiple(array $keys) {
+    $results = array();
+    // Foreach only needs to traverse $keys once, the PHP implementation
+    // array_intersect_key(array_flip(array_values($keys)), $this->data);
+    // would be slower.
+    foreach ($keys as $key) {
+      if (isset($this->data[$key])) {
+        $results[$key] = $this->data[$key];
+      }
+    }
+    return $results;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::getAll().
+   */
+  public function getAll() {
+    return $this->data;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::set().
+   */
+  public function set($key, $value) {
+    $this->data[$key] = $value;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::setMultiple().
+   */
+  public function setMultiple(array $data) {
+    $this->data = $data + $this->data;
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::delete().
+   */
+  public function delete($key) {
+    unset($this->data[$key]);
+  }
+
+  /**
+   * Implements KeyValueStore\Storage\StorageInterface::deleteMultiple().
+   */
+  public function deleteMultiple(array $keys) {
+    foreach ($keys as $key) {
+      unset($this->data[$key]);
+    }
+  }
+
+}
diff --git a/core/modules/color/lib/Drupal/color/Tests/ColorTest.php b/core/modules/color/lib/Drupal/color/Tests/ColorTest.php
index 8902d4c..22e34c6 100644
--- a/core/modules/color/lib/Drupal/color/Tests/ColorTest.php
+++ b/core/modules/color/lib/Drupal/color/Tests/ColorTest.php
@@ -108,7 +108,9 @@ class ColorTest extends WebTestBase {
     $config->set('preprocess.css', 1);
     $config->save();
     $this->drupalGet('<front>');
-    $stylesheets = variable_get('drupal_css_cache_files', array());
+    if (!$stylesheets = state()->get('drupal_css_cache_files')) {
+      $stylesheets = array();
+    }
     $stylesheet_content = '';
     foreach ($stylesheets as $key => $uri) {
       $stylesheet_content .= join("\n", file(drupal_realpath($uri)));
diff --git a/core/modules/field/field.api.php b/core/modules/field/field.api.php
index 1f76def..7364d4f 100644
--- a/core/modules/field/field.api.php
+++ b/core/modules/field/field.api.php
@@ -1551,7 +1551,7 @@ function hook_field_available_languages_alter(&$langcodes, $context) {
 function hook_field_attach_create_bundle($entity_type, $bundle) {
   // When a new bundle is created, the menu needs to be rebuilt to add the
   // Field UI menu item tabs.
-  variable_set('menu_rebuild_needed', TRUE);
+  state()->set('menu_rebuild_needed', TRUE);
 }
 
 /**
diff --git a/core/modules/field_ui/field_ui.module b/core/modules/field_ui/field_ui.module
index bde3f35..63cf18b 100644
--- a/core/modules/field_ui/field_ui.module
+++ b/core/modules/field_ui/field_ui.module
@@ -309,7 +309,7 @@ function field_ui_element_info() {
 function field_ui_field_attach_create_bundle($entity_type, $bundle) {
   // When a new bundle is created, the menu needs to be rebuilt to add our
   // menu item tabs.
-  variable_set('menu_rebuild_needed', TRUE);
+  state()->set('menu_rebuild_needed', TRUE);
 }
 
 /**
diff --git a/core/modules/image/image.module b/core/modules/image/image.module
index 41b0fc3..2936529 100644
--- a/core/modules/image/image.module
+++ b/core/modules/image/image.module
@@ -253,7 +253,7 @@ function image_form_system_file_system_settings_alter(&$form, &$form_state) {
  */
 function image_system_file_system_settings_submit($form, &$form_state) {
   if ($form['file_public_path']['#default_value'] !== $form_state['values']['file_public_path']) {
-    variable_set('menu_rebuild_needed', TRUE);
+    state()->set('menu_rebuild_needed', TRUE);
   }
 }
 
diff --git a/core/modules/search/search.admin.inc b/core/modules/search/search.admin.inc
index 9168510..57e5d6b 100644
--- a/core/modules/search/search.admin.inc
+++ b/core/modules/search/search.admin.inc
@@ -175,7 +175,7 @@ function search_admin_settings_submit($form, &$form_state) {
   if ($config->get('active_modules') != $new_modules) {
     $config->set('active_modules', $new_modules);
     drupal_set_message(t('The active search modules have been changed.'));
-    variable_set('menu_rebuild_needed', TRUE);
+    state()->set('menu_rebuild_needed', TRUE);
   }
   $config->save();
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Common/JavaScriptTest.php b/core/modules/system/lib/Drupal/system/Tests/Common/JavaScriptTest.php
index ba7a48b..a7afe31 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Common/JavaScriptTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Common/JavaScriptTest.php
@@ -346,11 +346,12 @@ class JavaScriptTest extends WebTestBase {
     ));
 
     // Store the expected key for the first item in the cache.
-    $cache = array_keys(variable_get('drupal_js_cache_files', array()));
+    $cache_files = state()->get('drupal_js_cache_files');
+    $cache = $cache_files ? array_keys($cache_files) : array();
     $expected_key = $cache[0];
 
     // Reset variables and add a file in a different scope first.
-    variable_del('drupal_js_cache_files');
+    state()->del('drupal_js_cache_files');
     drupal_static_reset('drupal_add_js');
     drupal_add_library('system', 'drupal');
     drupal_add_js('some/custom/javascript_file.js', array('scope' => 'footer'));
@@ -365,7 +366,8 @@ class JavaScriptTest extends WebTestBase {
     ));
 
     // Compare the expected key for the first file to the current one.
-    $cache = array_keys(variable_get('drupal_js_cache_files', array()));
+    $cache_files = state()->get('drupal_js_cache_files');
+    $cache = $cache_files ? array_keys($cache_files) : array();
     $key = $cache[0];
     $this->assertEqual($key, $expected_key, 'JavaScript aggregation is not affected by ordering in different scopes.');
   }
diff --git a/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/DatabaseStorageTest.php b/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/DatabaseStorageTest.php
new file mode 100644
index 0000000..c81f8e9
--- /dev/null
+++ b/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/DatabaseStorageTest.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Drupal\system\Tests\KeyValueStore;
+
+class DatabaseStorageTest extends StorageTestBase {
+
+  static function getInfo() {
+    return array(
+      'name' => 'Database Storage',
+      'description' => 'Test the key-value database storage.',
+      'group' => 'Key-value store'
+    );
+  }
+
+  protected function setUp() {
+    parent::setUp();
+    module_load_install('system');
+    $schema = system_schema();
+    db_create_table('keyvalue', $schema['keyvalue']);
+  }
+
+  protected function tearDown() {
+    db_drop_table('keyvalue');
+    parent::tearDown();
+  }
+}
diff --git a/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/MemoryStorageTest.php b/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/MemoryStorageTest.php
new file mode 100644
index 0000000..d3db3bc
--- /dev/null
+++ b/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/MemoryStorageTest.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Drupal\system\Tests\KeyValueStore;
+
+class MemoryStorageTest extends StorageTestBase {
+
+  static function getInfo() {
+    return array(
+      'name' => 'Memory Storage',
+      'description' => 'Test the key-value memory storage.',
+      'group' => 'Key-value store'
+    );
+  }
+
+}
diff --git a/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/StorageTestBase.php b/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/StorageTestBase.php
new file mode 100644
index 0000000..8fb38a0
--- /dev/null
+++ b/core/modules/system/lib/Drupal/system/Tests/KeyValueStore/StorageTestBase.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace Drupal\system\Tests\KeyValueStore;
+
+use Drupal\simpletest\UnitTestBase;
+
+class StorageTestBase extends UnitTestBase {
+  protected function setUp() {
+    parent::setUp();
+    $class = explode('\\', get_class($this));
+    $this->collection = end($class);
+    $storageClass = '\\Drupal\\Core\\KeyValueStore\\' . substr($this->collection, 0, -4);
+    $this->kv = new $storageClass($this->collection);
+  }
+
+  public function testSetGet() {
+    $this->assertEqual($this->kv->getCollectionName(), $this->collection);
+    // get-set test.
+    $this->kv->set('foo', 'bar');
+    $this->assertEqual('bar', $this->kv->get('foo'));
+    $this->kv->delete('foo');
+    $this->assertFalse($this->kv->get('foo'));
+
+    // multiple test.
+    $values = array('foo' => 'bar', 'baz' => 'qux');
+    $this->kv->setMultiple($values);
+    $result = $this->kv->getMultiple(array('foo', 'baz'));
+    $this->assertEqual($values, $result);
+    $result = $this->kv->getAll();
+    // $result might not equal to $values, the order is not defined for
+    // getAll().
+    $this->assertEqual(count($result), count($values));
+    foreach ($result as $key => $value) {
+      $this->assertEqual($values[$key], $value);
+    }
+    $this->kv->deleteMultiple(array_keys($values));
+    $this->assertFalse($this->kv->get('foo'));
+    $this->assertFalse($this->kv->get('bar'));
+    $this->assertFalse($this->kv->getMultiple(array('foo', 'baz')));
+  }
+}
diff --git a/core/modules/system/lib/Drupal/system/Tests/Menu/RebuildTest.php b/core/modules/system/lib/Drupal/system/Tests/Menu/RebuildTest.php
index b6e0ec2..9cf1080 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Menu/RebuildTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Menu/RebuildTest.php
@@ -38,7 +38,7 @@ class RebuildTest extends WebTestBase {
 
     // Now we enable the rebuild variable and send a request to rebuild the menu
     // item. Now 'admin' should exist.
-    variable_set('menu_rebuild_needed', TRUE);
+    state()->set('menu_rebuild_needed', TRUE);
     // The request should trigger the rebuild.
     $this->drupalGet('<front>');
     $admin_exists = db_query('SELECT path from {menu_router} WHERE path = :path', array(':path' => 'admin'))->fetchField();
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index ac983aa..0cca136 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -549,6 +549,60 @@ function system_schema() {
     ),
     'primary key' => array('name'),
   );
+  $schema['keyvalue'] = array(
+    'description' => 'Generic key-value storage table.',
+    'fields' => array(
+      'name' => array(
+        'description' => 'The key.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      'collection' => array(
+        'description' => 'The collection of the variable.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      'value' => array(
+        'description' => 'The value.',
+        'type' => 'blob',
+        'not null' => TRUE,
+        'size' => 'big',
+        'translatable' => TRUE,
+      ),
+    ),
+    'primary key' => array('collection', 'name'),
+  );
+  $schema['keyvalue'] = array(
+    'description' => 'Generic key-value storage table.',
+    'fields' => array(
+      'name' => array(
+       'description' => 'The key.',
+       'type' => 'varchar',
+       'length' => 128,
+       'not null' => TRUE,
+       'default' => '',
+      ),
+      'collection' => array(
+        'description' => 'The collection of the variable.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      'value' => array(
+        'description' => 'The value.',
+        'type' => 'blob',
+        'not null' => TRUE,
+        'size' => 'big',
+        'translatable' => TRUE,
+      ),
+    ),
+    'primary key' => array('collection', 'name'),
+  );
 
   $schema['actions'] = array(
     'description' => 'Stores action information.',