diff --git a/README.txt b/README.txt
index 5e49ac4..77a1d65 100644
--- a/README.txt
+++ b/README.txt
@@ -4,6 +4,7 @@ CONTENTS OF THIS FILE
 
  * About Drupal
  * Configuration and features
+ * Installation profiles
  * Appearance
  * Developing for Drupal
 
@@ -42,6 +43,35 @@ More about configuration:
    http://drupal.org/project/modules
  * See also: "Developing for Drupal" for writing your own modules, below.
 
+
+INSTALLATION PROFILES
+---------------------
+
+Installation profiles define additional steps (such as enabling modules,
+defining content types, etc.) that run after the base installation provided
+by core when Drupal is first installed. There are two basic installation
+profiles provided with Drupal core.
+
+Installation profiles from the Drupal community modify the installation process
+to provide a website for a specific use case, such as a CMS for media
+publishers, a web-based project tracking tool, or a full-fledged CRM for
+non-profit organizations raising money and accepting donations. They can be
+distributed as bare installation profiles or as "distributions". Distributions
+include Drupal core, the installation profile, and all other required
+extensions, such as contributed and custom modules, themes, and third-party
+libraries. Bare installation profiles require you to download Drupal Core and
+the required extensions separately; place the downloaded profile in the
+/profiles directory before you start the installation process.
+
+More about installation profiles and distributions:
+* Read about the difference between installation profiles and distributions:
+  http://drupal.org/node/1089736
+* Download contributed installation profiles and distributions:
+  http://drupal.org/project/distributions
+* Develop your own installation profile or distribution:
+  http://drupal.org/developing/distributions
+
+
 APPEARANCE
 ----------
 
diff --git a/core/lib/Drupal/Core/CoreBundle.php b/core/lib/Drupal/Core/CoreBundle.php
index c1abfe5..800d0ab 100644
--- a/core/lib/Drupal/Core/CoreBundle.php
+++ b/core/lib/Drupal/Core/CoreBundle.php
@@ -55,6 +55,10 @@ class CoreBundle extends Bundle
       ->setFactoryMethod('getConnection')
       ->addArgument('slave');
     $container->register('typed_data', 'Drupal\Core\TypedData\TypedDataManager');
+    $container->register('lock', 'Drupal\Core\Lock\DatabaseLockBackend');
+    $container->register('user.tempstore', 'Drupal\user\KeyValueStoreWithOwnerFactory')
+      ->addArgument(new Reference('database'))
+      ->addArgument(new Reference('lock'));
 
     $container->register('router.dumper', '\Drupal\Core\Routing\MatcherDumper')
       ->addArgument(new Reference('database'));
diff --git a/core/lib/Drupal/Core/FileTransfer/ChmodInterface.php b/core/lib/Drupal/Core/FileTransfer/ChmodInterface.php
index d9035f7..c1c68cb 100644
--- a/core/lib/Drupal/Core/FileTransfer/ChmodInterface.php
+++ b/core/lib/Drupal/Core/FileTransfer/ChmodInterface.php
@@ -18,7 +18,7 @@ interface ChmodInterface {
    * @param string $path
    *   Path to change permissions of.
    * @param int $mode
-   *   See the $mode argument from http://php.net/chmod.
+   *   The new file permission mode to be passed to chmod().
    * @param bool $recursive
    *   Pass TRUE to recursively chmod the entire directory specified in $path.
    *
diff --git a/core/lib/Drupal/Core/FileTransfer/FileTransfer.php b/core/lib/Drupal/Core/FileTransfer/FileTransfer.php
index 78d69d0..337b0b3 100644
--- a/core/lib/Drupal/Core/FileTransfer/FileTransfer.php
+++ b/core/lib/Drupal/Core/FileTransfer/FileTransfer.php
@@ -136,7 +136,7 @@ abstract class FileTransfer {
    * @param string $path
    *   The file / directory to change the permissions of.
    * @param int $mode
-   *   See the $mode argument from http://php.net/chmod.
+   *   The new file permission mode to be passed to chmod().
    * @param bool $recursive
    *   Pass TRUE to recursively chmod the entire directory specified in $path.
    *
diff --git a/core/lib/Drupal/Core/KeyValueStore/DatabaseStorage.php b/core/lib/Drupal/Core/KeyValueStore/DatabaseStorage.php
index 4484e9f..887bdfa 100644
--- a/core/lib/Drupal/Core/KeyValueStore/DatabaseStorage.php
+++ b/core/lib/Drupal/Core/KeyValueStore/DatabaseStorage.php
@@ -7,15 +7,28 @@
 
 namespace Drupal\Core\KeyValueStore;
 
+use Drupal\Core\Database\Query\Merge;
+
 /**
  * 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.
+ *
+ * @todo This class still calls db_* functions directly because it's needed
+ *   very early, pre-Container.  Once the early bootstrap dependencies are
+ *   sorted out, switch this to use an injected database connection.
  */
 class DatabaseStorage extends StorageBase {
 
   /**
+   * The name of the SQL table to use.
+   *
+   * @var string
+   */
+  protected $table;
+
+  /**
    * Overrides Drupal\Core\KeyValueStore\StorageBase::__construct().
    *
    * @param string $collection
@@ -44,9 +57,9 @@ class DatabaseStorage extends StorageBase {
       }
     }
     catch (\Exception $e) {
-      // @todo: Perhaps if the database is never going to be available,
-      // key/value requests should return FALSE in order to allow exception
-      // handling to occur but for now, keep it an array, always.
+      // @todo Perhaps if the database is never going to be available,
+      //   key/value requests should return FALSE in order to allow exception
+      //   handling to occur but for now, keep it an array, always.
     }
     return $values;
   }
@@ -80,6 +93,23 @@ class DatabaseStorage extends StorageBase {
   }
 
   /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::setIfNotExists().
+   */
+  public function setIfNotExists($key, $value) {
+    $result = db_merge($this->table)
+      ->insertFields(array(
+        'collection' => $this->collection,
+        'name' => $key,
+        'value' => $value,
+      ))
+      ->condition('collection', $this->collection)
+      ->condition('name', $key)
+      ->condition('value', $value)
+      ->execute();
+    return $result == Merge::STATUS_INSERT;
+  }
+
+  /**
    * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::deleteMultiple().
    */
   public function deleteMultiple(array $keys) {
@@ -93,4 +123,12 @@ class DatabaseStorage extends StorageBase {
     while (count($keys));
   }
 
+  /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::deleteAll().
+   */
+  public function deleteAll() {
+    db_delete($this->table)
+      ->condition('collection', $this->collection)
+      ->execute();
+  }
 }
diff --git a/core/lib/Drupal/Core/KeyValueStore/DatabaseStorageExpirable.php b/core/lib/Drupal/Core/KeyValueStore/DatabaseStorageExpirable.php
new file mode 100644
index 0000000..0082f75
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/DatabaseStorageExpirable.php
@@ -0,0 +1,145 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\Core\KeyValueStore\DatabaseStorageExpirable.
+ */
+
+namespace Drupal\Core\KeyValueStore;
+
+use Drupal\Core\Database\Query\Merge;
+
+/**
+ * Defines a default key/value store implementation for expiring items.
+ *
+ * This is Drupal's default key/value store implementation. It uses the database
+ * to store key/value data with an expire date.
+ */
+class DatabaseStorageExpirable extends DatabaseStorage implements KeyValueStoreExpirableInterface {
+
+  /**
+   * The connection object for this storage.
+   *
+   * @var Drupal\Core\Database\Connection
+   */
+  protected $connection;
+
+  /**
+   * Overrides Drupal\Core\KeyValueStore\StorageBase::__construct().
+   *
+   * @param string $collection
+   *   The name of the collection holding key and value pairs.
+   * @param array $options
+   *   An associative array of options for the key/value storage collection.
+   *   Keys used:
+   *   - table. The name of the SQL table to use, defaults to key_value_expire.
+   */
+  public function __construct($collection, array $options = array()) {
+    parent::__construct($collection, $options);
+    $this->connection = $options['connection'];
+    $this->table = isset($options['table']) ? $options['table'] : 'key_value_expire';
+  }
+
+  /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::getMultiple().
+   */
+  public function getMultiple(array $keys) {
+    $values = array();
+    try {
+      $result = $this->connection->query('SELECT name, value, expire FROM {' . $this->connection->escapeTable($this->table) . '} WHERE expire > :now AND name IN (:keys) AND collection = :collection',
+        array(
+          ':now' => REQUEST_TIME,
+          ':keys' => $keys,
+          ':collection' => $this->collection,
+      ))->fetchAllAssoc('name');
+      foreach ($keys as $key) {
+        if (isset($result[$key])) {
+          $values[$key] = unserialize($result[$key]->value);
+        }
+      }
+    }
+    catch (\Exception $e) {
+      // @todo Perhaps if the database is never going to be available,
+      //   key/value requests should return FALSE in order to allow exception
+      //   handling to occur but for now, keep it an array, always.
+    }
+    return $values;
+  }
+
+  /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::getAll().
+   */
+  public function getAll() {
+    $result = $this->connection->query('SELECT name, value FROM {' . $this->connection->escapeTable($this->table) . '} WHERE collection = :collection AND expire > :now', array(':collection' => $this->collection, ':now' => REQUEST_TIME));
+    $values = array();
+
+    foreach ($result as $item) {
+      if ($item) {
+        $values[$item->name] = unserialize($item->value);
+      }
+    }
+    return $values;
+  }
+
+  /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreExpireInterface::setWithExpire().
+   */
+  function setWithExpire($key, $value, $expire) {
+    $this->garbageCollection();
+    $this->connection->merge($this->table)
+      ->key(array(
+        'name' => $key,
+        'collection' => $this->collection,
+      ))
+      ->fields(array(
+        'value' => serialize($value),
+        'expire' => REQUEST_TIME + $expire,
+      ))
+      ->execute();
+  }
+
+  /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::setWithExpireIfNotExists().
+   */
+  function setWithExpireIfNotExists($key, $value, $expire) {
+    $this->garbageCollection();
+    $result = $this->connection->merge($this->table)
+      ->insertFields(array(
+        'collection' => $this->collection,
+        'name' => $key,
+        'value' => serialize($value),
+        'expire' => REQUEST_TIME + $expire,
+      ))
+      ->condition('collection', $this->collection)
+      ->condition('name', $key)
+      ->execute();
+    return $result == MERGE::STATUS_INSERT;
+  }
+
+  /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::setMultipleWithExpire().
+   */
+  function setMultipleWithExpire(array $data, $expire) {
+    foreach ($data as $key => $value) {
+      $this->set($key, $value, $expire);
+    }
+  }
+
+  /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::deleteMultiple().
+   */
+  public function deleteMultiple(array $keys) {
+    $this->garbageCollection();
+    parent::deleteMultiple($keys);
+  }
+
+  /**
+   * Deletes expired items.
+   */
+  protected function garbageCollection() {
+    $this->connection->delete($this->table)
+      ->condition('expire', REQUEST_TIME, '<')
+      ->execute();
+  }
+
+}
diff --git a/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreExpirableInterface.php b/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreExpirableInterface.php
new file mode 100644
index 0000000..113c6c6
--- /dev/null
+++ b/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreExpirableInterface.php
@@ -0,0 +1,52 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\Core\KeyValueStore\KeyValueStoreExpirableInterface.
+ */
+
+namespace Drupal\Core\KeyValueStore;
+
+/**
+ * Defines the interface for expiring date in a key/value store.
+ */
+interface KeyValueStoreExpirableInterface extends KeyValueStoreInterface {
+
+  /**
+   * Saves a value for a given key with a time to live.
+   *
+   * @param string $key
+   *   The key of the data to store.
+   * @param mixed $value
+   *   The data to store.
+   * @param int $expire
+   *   The time to live for items, in seconds.
+   */
+  function setWithExpire($key, $value, $expire);
+
+  /**
+   * Sets a value for a given key with a time to live, if it does not exist yet.
+   *
+   * @param string $key
+   *   The key of the data to store.
+   * @param mixed $value
+   *   The data to store.
+   * @param int $expire
+   *   The time to live for items, in seconds.
+   *
+   * @return bool
+   *   TRUE if the data was set, FALSE if it already existed.
+   */
+  function setWithExpireIfNotExists($key, $value, $expire);
+
+  /**
+   * Saves an array of values with a time to live.
+   *
+   * @param array $data
+   *   An array of data to store.
+   * @param int $expire
+   *   The time to live for items, in seconds.
+   */
+  function setMultipleWithExpire(array $data, $expire);
+
+}
diff --git a/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreInterface.php b/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreInterface.php
index 9e7bb34..1a6c467 100644
--- a/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreInterface.php
+++ b/core/lib/Drupal/Core/KeyValueStore/KeyValueStoreInterface.php
@@ -73,6 +73,19 @@ interface KeyValueStoreInterface {
   public function set($key, $value);
 
   /**
+   * Saves a value for a given key if it does not exist yet.
+   *
+   * @param string $key
+   *   The key of the data to store.
+   * @param mixed $value
+   *   The data to store.
+   *
+   * @return bool
+   *   TRUE if the data was set, FALSE if it already existed.
+   */
+  public function setIfNotExists($key, $value);
+
+  /**
    * Saves key/value pairs.
    *
    * @param array $data
@@ -96,4 +109,9 @@ interface KeyValueStoreInterface {
    */
   public function deleteMultiple(array $keys);
 
+  /**
+   * Deletes all items from the key/value store.
+   */
+  public function deleteAll();
+
 }
diff --git a/core/lib/Drupal/Core/KeyValueStore/MemoryStorage.php b/core/lib/Drupal/Core/KeyValueStore/MemoryStorage.php
index 4724005..6f6aca5 100644
--- a/core/lib/Drupal/Core/KeyValueStore/MemoryStorage.php
+++ b/core/lib/Drupal/Core/KeyValueStore/MemoryStorage.php
@@ -65,6 +65,17 @@ class MemoryStorage implements KeyValueStoreInterface {
   }
 
   /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::setIfNotExists().
+   */
+  public function setIfNotExists($key, $value) {
+    if (!isset($this->data[$key])) {
+      $this->data[$key] = $value;
+      return TRUE;
+    }
+    return FALSE;
+  }
+
+  /**
    * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::setMultiple().
    */
   public function setMultiple(array $data) {
@@ -87,4 +98,10 @@ class MemoryStorage implements KeyValueStoreInterface {
     }
   }
 
+  /**
+   * Implements Drupal\Core\KeyValueStore\KeyValueStoreInterface::deleteAll().
+   */
+  public function deleteAll() {
+    $this->data = array();
+  }
 }
diff --git a/core/modules/comment/comment.admin.inc b/core/modules/comment/comment.admin.inc
index 4a3220f..ef8a90b 100644
--- a/core/modules/comment/comment.admin.inc
+++ b/core/modules/comment/comment.admin.inc
@@ -110,13 +110,14 @@ function comment_admin_overview($form, &$form_state, $arg) {
     // Remove the first node title from the node_titles array and attach to
     // the comment.
     $comment->node_title = array_shift($node_titles);
+    $comment_body = field_get_items('comment', $comment, 'comment_body');
     $options[$comment->cid] = array(
       'subject' => array(
         'data' => array(
           '#type' => 'link',
           '#title' => $comment->subject,
           '#href' => 'comment/' . $comment->cid,
-          '#options' => array('attributes' => array('title' => truncate_utf8($comment->comment_body[LANGUAGE_NOT_SPECIFIED][0]['value'], 128)), 'fragment' => 'comment-' . $comment->cid),
+          '#options' => array('attributes' => array('title' => truncate_utf8($comment_body[0]['value'], 128)), 'fragment' => 'comment-' . $comment->cid),
         ),
       ),
       'author' => theme('username', array('account' => $comment)),
diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index 44b4c04..27ff7c3 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -1690,7 +1690,8 @@ function comment_preview(Comment $comment) {
   $node = node_load($comment->nid);
 
   if (!form_get_errors()) {
-    $comment->format = $comment->comment_body[LANGUAGE_NOT_SPECIFIED][0]['format'];
+    $comment_body = field_get_items('comment', $comment, 'comment_body');
+    $comment->format = $comment_body[0]['format'];
     // Attach the user and time information.
     if (!empty($comment->name)) {
       $account = user_load_by_name($comment->name);
diff --git a/core/modules/comment/lib/Drupal/comment/CommentFormController.php b/core/modules/comment/lib/Drupal/comment/CommentFormController.php
index 7dae92d..cead0cd 100644
--- a/core/modules/comment/lib/Drupal/comment/CommentFormController.php
+++ b/core/modules/comment/lib/Drupal/comment/CommentFormController.php
@@ -20,7 +20,6 @@ class CommentFormController extends EntityFormController {
    */
   public function form(array $form, array &$form_state, EntityInterface $comment) {
     global $user;
-    $language_content = language(LANGUAGE_TYPE_CONTENT);
 
     $node = node_load($comment->nid);
     $form_state['comment']['node'] = $node;
@@ -174,16 +173,16 @@ class CommentFormController extends EntityFormController {
     }
     $form['node_type'] = array('#type' => 'value', '#value' => 'comment_node_' . $node->type);
 
-    // Make the comment inherit the node language unless specifically set.
-    $comment_langcode = $comment->langcode;
-    if ($comment_langcode == LANGUAGE_NOT_SPECIFIED) {
-      $comment_langcode = $language_content->langcode;
+    // Make the comment inherit the current content language unless specifically
+    // set.
+    if ($comment->isNew()) {
+      $language_content = language(LANGUAGE_TYPE_CONTENT);
+      $comment->langcode = $language_content->langcode;
     }
 
-    // Uses the language of the content as comment language.
     $form['langcode'] = array(
       '#type' => 'value',
-      '#value' => $comment_langcode,
+      '#value' => $comment->langcode,
     );
 
     // Attach fields.
@@ -294,7 +293,9 @@ class CommentFormController extends EntityFormController {
       // 1) Filter it into HTML
       // 2) Strip out all HTML tags
       // 3) Convert entities back to plain-text.
-      $comment_body = $comment->comment_body[LANGUAGE_NOT_SPECIFIED][0];
+      $field = field_info_field('comment_body');
+      $langcode = field_is_translatable('comment', $field) ? $this->getFormLangcode($form_state) : LANGUAGE_NOT_SPECIFIED;
+      $comment_body = $comment->comment_body[$langcode][0];
       if (isset($comment_body['format'])) {
         $comment_text = check_markup($comment_body['value'], $comment_body['format']);
       }
diff --git a/core/modules/locale/lib/Drupal/locale/Tests/LocaleCommentLanguageTest.php b/core/modules/comment/lib/Drupal/comment/Tests/CommentLanguageTest.php
similarity index 69%
rename from core/modules/locale/lib/Drupal/locale/Tests/LocaleCommentLanguageTest.php
rename to core/modules/comment/lib/Drupal/comment/Tests/CommentLanguageTest.php
index 6776e31..9c3af8e 100644
--- a/core/modules/locale/lib/Drupal/locale/Tests/LocaleCommentLanguageTest.php
+++ b/core/modules/comment/lib/Drupal/comment/Tests/CommentLanguageTest.php
@@ -2,17 +2,17 @@
 
 /**
  * @file
- * Definition of Drupal\locale\Tests\LocaleCommentLanguageTest.
+ * Definition of Drupal\comment\Tests\CommentLanguageTest.
  */
 
-namespace Drupal\locale\Tests;
+namespace Drupal\comment\Tests;
 
 use Drupal\simpletest\WebTestBase;
 
 /**
  * Functional tests for comment language.
  */
-class LocaleCommentLanguageTest extends WebTestBase {
+class CommentLanguageTest extends WebTestBase {
 
   /**
    * Modules to enable.
@@ -23,7 +23,7 @@ class LocaleCommentLanguageTest extends WebTestBase {
    *
    * @var array
    */
-  public static $modules = array('locale', 'language_test');
+  public static $modules = array('language', 'language_test', 'comment_test');
 
   protected $profile = 'standard';
 
@@ -31,7 +31,7 @@ class LocaleCommentLanguageTest extends WebTestBase {
     return array(
       'name' => 'Comment language',
       'description' => 'Tests for comment language.',
-      'group' => 'Locale',
+      'group' => 'Comment',
     );
   }
 
@@ -39,7 +39,7 @@ class LocaleCommentLanguageTest extends WebTestBase {
     parent::setUp();
 
     // Create and login user.
-    $admin_user = $this->drupalCreateUser(array('administer site configuration', 'administer languages', 'access administration pages', 'administer content types', 'create article content'));
+    $admin_user = $this->drupalCreateUser(array('administer site configuration', 'administer languages', 'access administration pages', 'administer content types', 'administer comments', 'create article content'));
     $this->drupalLogin($admin_user);
 
     // Add language.
@@ -68,6 +68,12 @@ class LocaleCommentLanguageTest extends WebTestBase {
     // French no matter what path prefix the URLs have.
     $edit = array('preferred_langcode' => 'fr');
     $this->drupalPost("user/{$admin_user->uid}/edit", $edit, t('Save'));
+
+    // Make comment body translatable.
+    $field = field_info_field('comment_body');
+    $field['translatable'] = TRUE;
+    field_update_field($field);
+    $this->assertTrue(field_is_translatable('comment', $field), 'Comment body is translatable.');
   }
 
   /**
@@ -99,19 +105,36 @@ class LocaleCommentLanguageTest extends WebTestBase {
       foreach (language_list() as $langcode => $language) {
         // Post a comment with content language $langcode.
         $prefix = empty($prefixes[$langcode]) ? '' : $prefixes[$langcode] . '/';
-        $edit = array("comment_body[$langcode_not_specified][0][value]" => $this->randomName());
-        $this->drupalPost("{$prefix}node/{$node->nid}", $edit, t('Save'));
+        $comment_values[$node_langcode][$langcode] = $this->randomName();
+        $edit = array(
+          'subject' => $this->randomName(),
+          "comment_body[$langcode][0][value]" => $comment_values[$node_langcode][$langcode],
+        );
+        $this->drupalPost("{$prefix}node/{$node->nid}", $edit, t('Preview'));
+        $this->drupalPost(NULL, $edit, t('Save'));
 
         // Check that comment language matches the current content language.
-        $comment = db_select('comment', 'c')
-          ->fields('c')
+        $cid = db_select('comment', 'c')
+          ->fields('c', array('cid'))
           ->condition('nid', $node->nid)
           ->orderBy('cid', 'DESC')
+          ->range(0, 1)
           ->execute()
-          ->fetchObject();
+          ->fetchField();
+        $comment = comment_load($cid);
         $args = array('%node_language' => $node_langcode, '%comment_language' => $comment->langcode, '%langcode' => $langcode);
-        $this->assertEqual($comment->langcode, $langcode, t('The comment posted with content language %langcode and belonging to the node with language %node_language has language %comment_language', $args));
+        $this->assertEqual($comment->langcode, $langcode, format_string('The comment posted with content language %langcode and belonging to the node with language %node_language has language %comment_language', $args));
+        $this->assertEqual($comment->comment_body[$langcode][0]['value'], $comment_values[$node_langcode][$langcode], 'Comment body correctly stored.');
+      }
+    }
+
+    // Check that comment bodies appear in the administration UI.
+    $this->drupalGet('admin/content/comment');
+    foreach ($comment_values as $node_values) {
+      foreach ($node_values as $value) {
+        $this->assertRaw($value);
       }
     }
   }
+
 }
diff --git a/core/modules/comment/tests/modules/comment_test/comment_test.info b/core/modules/comment/tests/modules/comment_test/comment_test.info
new file mode 100644
index 0000000..a7ad565
--- /dev/null
+++ b/core/modules/comment/tests/modules/comment_test/comment_test.info
@@ -0,0 +1,8 @@
+name = Comment test
+description = Support module for Comment module testing.
+package = Testing
+version = VERSION
+core = 8.x
+hidden = TRUE
+
+dependencies[] = comment
diff --git a/core/modules/comment/tests/modules/comment_test/comment_test.module b/core/modules/comment/tests/modules/comment_test/comment_test.module
new file mode 100644
index 0000000..8e903db
--- /dev/null
+++ b/core/modules/comment/tests/modules/comment_test/comment_test.module
@@ -0,0 +1,17 @@
+<?php
+
+/**
+ * @file
+ * Dummy module implementing comment related hooks to test API interaction with
+ * the Comment module.
+ */
+
+/**
+ * Implements hook_entity_info_alter().
+ */
+function comment_test_entity_info_alter(&$info) {
+  if (language_multilingual()) {
+    // Enable language handling for comment fields.
+    $info['comment']['translation']['comment_test'] = TRUE;
+  }
+}
diff --git a/core/modules/field/field.multilingual.inc b/core/modules/field/field.multilingual.inc
index f84b30a..d5863d9 100644
--- a/core/modules/field/field.multilingual.inc
+++ b/core/modules/field/field.multilingual.inc
@@ -301,7 +301,7 @@ function field_valid_language($langcode, $default = TRUE) {
  */
 function field_language($entity_type, $entity, $field_name = NULL, $langcode = NULL) {
   $display_langcodes = &drupal_static(__FUNCTION__, array());
-  $id = $entity->bundle();
+  $id = $entity->id();
   $bundle = $entity->bundle();
   $langcode = field_valid_language($langcode, FALSE);
 
diff --git a/core/modules/overlay/overlay-child-rtl.css b/core/modules/overlay/overlay-child-rtl.css
index febaab3..0c5edcb 100644
--- a/core/modules/overlay/overlay-child-rtl.css
+++ b/core/modules/overlay/overlay-child-rtl.css
@@ -1,4 +1,9 @@
 
+/**
+ * @file
+ * RTL styling for Overlay child pages.
+ */
+
 html {
   direction: rtl;
 }
diff --git a/core/modules/overlay/overlay-child.css b/core/modules/overlay/overlay-child.css
index 5ca0b4f..7afbe25 100644
--- a/core/modules/overlay/overlay-child.css
+++ b/core/modules/overlay/overlay-child.css
@@ -1,4 +1,9 @@
 
+/**
+ * @file
+ * Basic styling for the Overlay child pages.
+ */
+
 .js {
   background: transparent !important;
   overflow-y: scroll;
diff --git a/core/modules/overlay/overlay-child.js b/core/modules/overlay/overlay-child.js
index 39b6efb..80a8a2f 100644
--- a/core/modules/overlay/overlay-child.js
+++ b/core/modules/overlay/overlay-child.js
@@ -1,3 +1,8 @@
+/**
+ * @file
+ * Attaches the behaviors for the Overlay child pages.
+ */
+
 (function ($) {
 
 "use strict";
diff --git a/core/modules/overlay/overlay-parent.css b/core/modules/overlay/overlay-parent.css
index dad6d55..9459a7a 100644
--- a/core/modules/overlay/overlay-parent.css
+++ b/core/modules/overlay/overlay-parent.css
@@ -1,4 +1,9 @@
 
+/**
+ * @file
+ * Basic styling for the Overlay module.
+ */
+
 html.overlay-open,
 html.overlay-open body {
   height: 100%;
diff --git a/core/modules/overlay/overlay-parent.js b/core/modules/overlay/overlay-parent.js
index 678d68a..1f38f2f 100644
--- a/core/modules/overlay/overlay-parent.js
+++ b/core/modules/overlay/overlay-parent.js
@@ -1,3 +1,8 @@
+/**
+ * @file
+ * Attaches the behaviors for the Overlay parent pages.
+ */
+
 (function ($) {
 
 "use strict";
diff --git a/core/modules/overlay/overlay.install b/core/modules/overlay/overlay.install
index 2fa7c84..5fc2936 100644
--- a/core/modules/overlay/overlay.install
+++ b/core/modules/overlay/overlay.install
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Install, update and uninstall functions for the overlay module.
+ * Install, update, and uninstall functions for the Overlay module.
  */
 
 /**
diff --git a/core/modules/overlay/overlay.module b/core/modules/overlay/overlay.module
index 3ae575c..e2cdc4c 100644
--- a/core/modules/overlay/overlay.module
+++ b/core/modules/overlay/overlay.module
@@ -331,7 +331,7 @@ function overlay_user_dismiss_message_access() {
 }
 
 /**
- * Menu callback; dismisses the overlay accessibility message for this user.
+ * Menu callback: Dismisses the overlay accessibility message for this user.
  *
  * @see overlay_user_dismiss_message_access()
  * @see overlay_menu()
@@ -361,10 +361,12 @@ function overlay_user_dismiss_message() {
  * If the current user can access the overlay and has not previously indicated
  * that this message should be dismissed, this function returns a message
  * containing a link to disable the overlay. Nothing is returned for anonymous
- * users, because the links control per-user settings. Therefore, because some
- * screen readers are unable to properly read overlay contents, site builders
- * are discouraged from granting the "access overlay" permission to the
- * anonymous role. See http://drupal.org/node/890284.
+ * users, because the links control per-user settings. Because some screen
+ * readers are unable to properly read overlay contents, site builders are
+ * discouraged from granting the "access overlay" permission to the anonymous
+ * role.
+ *
+ * @see http://drupal.org/node/890284
  */
 function overlay_disable_message() {
   global $user;
@@ -419,7 +421,13 @@ function overlay_disable_message() {
 /**
  * Returns the HTML for the message about how to disable the overlay.
  *
- * @see overlay_disable_message()
+ * @param $variables
+ *   An associative array with an 'element' element, which itself is an
+ *   associative array containing:
+ *   - profile_link: The link to this user's account.
+ *   - dismiss_message_link: The link to dismiss the overlay.
+ *
+ * @ingroup themeable
  */
 function theme_overlay_disable_message($variables) {
   $element = $variables['element'];
@@ -505,8 +513,12 @@ function overlay_preprocess_maintenance_page(&$variables) {
 }
 
 /**
- * Preprocesses template variables for overlay.tpl.php
+ * Implements template_preprocess_HOOK() for overlay.tpl.php
+ *
+ * If the current page request is inside the overlay, add appropriate classes
+ * to the <body> element, and simplify the page title.
  *
+ * @see template_process_overlay()
  * @see overlay.tpl.php
  */
 function template_preprocess_overlay(&$variables) {
@@ -517,20 +529,21 @@ function template_preprocess_overlay(&$variables) {
 }
 
 /**
- * Processes variables for overlay.tpl.php
+ * Implements template_process_HOOK() for overlay.tpl.php
+ *
+ * Places the rendered HTML for the page body into a top level variable.
  *
  * @see template_preprocess_overlay()
  * @see overlay.tpl.php
  */
 function template_process_overlay(&$variables) {
-  // Place the rendered HTML for the page body into a top level variable.
   $variables['page'] = $variables['page']['#children'];
 }
 
 /**
  * Implements hook_preprocess_HOOK() for page.tpl.php.
  *
- * Hide tabs inside the overlay.
+ * If the current page request is inside the overlay, hide the tabs.
  *
  * @see overlay_get_mode()
  */
@@ -582,7 +595,7 @@ function overlay_page_delivery_callback_alter(&$callback) {
 }
 
 /**
- * Delivery callback to display an empty page.
+ * Prints an empty page.
  *
  * This function is used to print out a bare minimum empty page which still has
  * the scripts and styles necessary in order to trigger the overlay to close.
@@ -594,7 +607,7 @@ function overlay_deliver_empty_page() {
 }
 
 /**
- * Get the current overlay mode.
+ * Gets the current overlay mode.
  *
  * @see overlay_set_mode()
  */
@@ -787,7 +800,7 @@ function overlay_supplemental_regions() {
 }
 
 /**
- * Helper function for returning a list of page regions related to the overlay.
+ * Returns a list of page regions related to the overlay.
  *
  * @param $type
  *   The type of regions to return. This can either be 'overlay_regions' or
diff --git a/core/modules/overlay/overlay.tpl.php b/core/modules/overlay/overlay.tpl.php
index 622247b..38e6664 100644
--- a/core/modules/overlay/overlay.tpl.php
+++ b/core/modules/overlay/overlay.tpl.php
@@ -9,6 +9,9 @@
  * - $page: The rendered page content.
  * - $tabs (array): Tabs linking to any sub-pages beneath the current page
  *   (e.g., the view and edit tabs when displaying a node).
+ * Helper variables:
+ * - $classes_array: Array of HMTL class attribute values. It is flattened into
+ *   a string within the variable $classes.
  *
  * @see template_preprocess()
  * @see template_preprocess_overlay()
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 05459d0..9ae0bba 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -832,6 +832,43 @@ function system_schema() {
     'primary key' => array('collection', 'name'),
   );
 
+  $schema['key_value_expire'] = array(
+    'description' => 'Generic key-value storage table with an expire.',
+    'fields' => array(
+      'collection' => array(
+        'description' => 'A named collection of key and value pairs.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      'name' => array(
+        'description' => 'The key of the key-value pair. As KEY is a SQL reserved keyword, name was chosen instead.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      'value' => array(
+        'description' => 'The value.',
+        'type' => 'blob',
+        'not null' => TRUE,
+        'size' => 'big',
+        'translatable' => TRUE,
+      ),
+      'expire' => array(
+        'description' => 'The time since Unix epoch in seconds when this item expires.',
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+      ),
+    ),
+    'primary key' => array('collection', 'name'),
+    'indexes' => array(
+      'all' => array('name', 'collection', 'expire'),
+    ),
+  );
+
   $schema['menu_router'] = array(
     'description' => 'Maps paths to various callbacks (access, page and title)',
     'fields' => array(
@@ -2102,6 +2139,50 @@ function system_update_8022() {
 }
 
 /**
+ * Create the 'key_value_expire' table.
+ */
+function system_update_8023() {
+  $table = array(
+    'description' => 'Generic key-value storage table with an expire.',
+    'fields' => array(
+      'collection' => array(
+        'description' => 'A named collection of key and value pairs.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      'name' => array(
+        'description' => 'The key of the key-value pair. As KEY is a SQL reserved keyword, name was chosen instead.',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+        'default' => '',
+      ),
+      'value' => array(
+        'description' => 'The value.',
+        'type' => 'blob',
+        'not null' => TRUE,
+        'size' => 'big',
+        'translatable' => TRUE,
+      ),
+      'expire' => array(
+        'description' => 'The time since Unix epoch in seconds when this item expires.',
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+      ),
+    ),
+    'primary key' => array('collection', 'name'),
+    'indexes' => array(
+      'all' => array('name', 'collection', 'expire'),
+    ),
+  );
+
+  db_create_table('key_value_expire', $table);
+}
+
+/**
  * @} End of "defgroup updates-7.x-to-8.x".
  * The next series of updates should start at 9000.
  */
diff --git a/core/modules/system/theme.api.php b/core/modules/system/theme.api.php
index 0001cba..a697eef 100644
--- a/core/modules/system/theme.api.php
+++ b/core/modules/system/theme.api.php
@@ -234,5 +234,5 @@ function hook_themes_enabled($theme_list) {
  */
 function hook_themes_disabled($theme_list) {
  // Clear all update module caches.
-  _update_cache_clear();
+  update_storage_clear();
 }
diff --git a/core/modules/update/lib/Drupal/update/Tests/UpdateCoreTest.php b/core/modules/update/lib/Drupal/update/Tests/UpdateCoreTest.php
index 5dc09fd..dd9626b 100644
--- a/core/modules/update/lib/Drupal/update/Tests/UpdateCoreTest.php
+++ b/core/modules/update/lib/Drupal/update/Tests/UpdateCoreTest.php
@@ -210,8 +210,8 @@ class UpdateCoreTest extends UpdateTestBase {
     update_create_fetch_task($projecta);
     $this->assertEqual($queue->numberOfItems(), 2, 'Queue still contains two items');
 
-    // Clear cache and try again.
-    _update_cache_clear();
+    // Clear storage and try again.
+    update_storage_clear();
     drupal_static_reset('_update_create_fetch_task');
     update_create_fetch_task($projecta);
     $this->assertEqual($queue->numberOfItems(), 2, 'Queue contains two items');
diff --git a/core/modules/update/update.authorize.inc b/core/modules/update/update.authorize.inc
index d22f235..396fa75 100644
--- a/core/modules/update/update.authorize.inc
+++ b/core/modules/update/update.authorize.inc
@@ -177,7 +177,7 @@ function update_authorize_batch_copy_project($project, $updater_name, $local_url
  *
  * This processes the results and stashes them into SESSION such that
  * authorize.php will render a report. Also responsible for putting the site
- * back online and clearing the update status cache after a successful update.
+ * back online and clearing the update status storage after a successful update.
  *
  * @param $success
  *   TRUE if the batch operation was successful; FALSE if there were errors.
@@ -192,8 +192,8 @@ function update_authorize_update_batch_finished($success, $results) {
   }
   $offline = config('system.maintenance')->get('enabled');
   if ($success) {
-    // Now that the update completed, we need to clear the cache of available
-    // update data and recompute our status, so prevent show bogus results.
+    // Now that the update completed, we need to clear the available update data
+    // and recompute our status, so prevent show bogus results.
     _update_authorize_clear_update_status();
 
     // Take the site out of maintenance mode if it was previously that way.
@@ -314,25 +314,19 @@ function _update_batch_create_message(&$project_results, $message, $success = TR
 }
 
 /**
- * Clears cached available update status data.
+ * Clears available update status data.
  *
  * Since this function is run at such a low bootstrap level, the Update Manager
- * module is not loaded. So, we can't just call _update_cache_clear(). However,
- * the database is bootstrapped, so we can do a query ourselves to clear out
- * what we want to clear.
+ * module is not loaded. So, we can't just call update_storage_clear(). However,
+ * the key-value backend is available, so we just call that.
  *
- * Note that we do not want to just truncate the table, since that would remove
- * items related to currently pending fetch attempts.
+ * Note that we do not want to delete  items related to currently pending fetch
+ * attempts.
  *
  * @see update_authorize_update_batch_finished()
- * @see _update_cache_clear()
+ * @see update_storage_clear()
  */
 function _update_authorize_clear_update_status() {
-  $query = db_delete('cache_update');
-  $query->condition(
-    db_or()
-    ->condition('cid', 'update_project_%', 'LIKE')
-    ->condition('cid', 'available_releases::%', 'LIKE')
-  );
-  $query->execute();
+  DatabaseStorageExpirable('update', array('connection' => Database::getConnection()))->deleteAll();
+  DatabaseStorageExpirable('update_available_releases', array('connection' => Database::getConnection()))->deleteAll();
 }
diff --git a/core/modules/update/update.compare.inc b/core/modules/update/update.compare.inc
index 2262404..9d0aa4b 100644
--- a/core/modules/update/update.compare.inc
+++ b/core/modules/update/update.compare.inc
@@ -16,13 +16,12 @@
  * fetching the available release data.
  *
  * This array is fairly expensive to construct, since it involves a lot of disk
- * I/O, so we cache the results into the {cache_update} table using the
- * 'update_project_projects' cache ID. However, since this is not the data about
+ * I/O, so we store the results. However, since this is not the data about
  * available updates fetched from the network, it is acceptable to invalidate it
  * somewhat quickly. If we keep this data for very long, site administrators are
  * more likely to see incorrect results if they upgrade to a newer version of a
  * module or theme but do not visit certain pages that automatically clear this
- * cache.
+ * data.
  *
  * @return
  *   An associative array of currently enabled projects keyed by the
@@ -51,15 +50,15 @@
  *
  * @see update_process_project_info()
  * @see update_calculate_project_data()
- * @see update_project_cache()
+ * @see update_project_storage()
  */
 function update_get_projects() {
   $projects = &drupal_static(__FUNCTION__, array());
   if (empty($projects)) {
-    // Retrieve the projects from cache, if present.
-    $projects = update_project_cache('update_project_projects');
+    // Retrieve the projects from storage, if present.
+    $projects = update_project_storage('update_project_projects');
     if (empty($projects)) {
-      // Still empty, so we have to rebuild the cache.
+      // Still empty, so we have to rebuild.
       $module_data = system_rebuild_module_data();
       $theme_data = system_rebuild_theme_data();
       update_process_info_list($projects, $module_data, 'module', TRUE);
@@ -70,8 +69,8 @@ function update_get_projects() {
       }
       // Allow other modules to alter projects before fetching and comparing.
       drupal_alter('update_projects', $projects);
-      // Cache the site's project data for at most 1 hour.
-      _update_cache_set('update_project_projects', $projects, REQUEST_TIME + 3600);
+      // Store the site's project data for at most 1 hour.
+      update_storage()->setWithExpire('update_project_projects', $projects, 3600);
     }
   }
   return $projects;
@@ -89,7 +88,7 @@ function update_get_projects() {
  * enabled code. Modules and themes set as hidden are always ignored. This
  * function also records the latest change time on the .info files for each
  * module or theme, which is important data which is used when deciding if the
- * cached available update data should be invalidated.
+ * available update data should be invalidated.
  *
  * @param $projects
  *   Reference to the array of project data of what's installed on this site.
@@ -316,13 +315,12 @@ function update_process_project_info(&$projects) {
  *
  * The results of this function are expensive to compute, especially on sites
  * with lots of modules or themes, since it involves a lot of comparisons and
- * other operations. Therefore, we cache the results into the {cache_update}
- * table using the 'update_project_data' cache ID. However, since this is not
+ * other operations. Therefore, we store the results. However, since this is not
  * the data about available updates fetched from the network, it is ok to
  * invalidate it somewhat quickly. If we keep this data for very long, site
  * administrators are more likely to see incorrect results if they upgrade to a
  * newer version of a module or theme but do not visit certain pages that
- * automatically clear this cache.
+ * automatically clear this.
  *
  * @param array $available
  *   Data about available project releases.
@@ -333,13 +331,13 @@ function update_process_project_info(&$projects) {
  * @see update_get_available()
  * @see update_get_projects()
  * @see update_process_project_info()
- * @see update_project_cache()
+ * @see update_project_storage()
  */
 function update_calculate_project_data($available) {
-  // Retrieve the projects from cache, if present.
-  $projects = update_project_cache('update_project_data');
-  // If $projects is empty, then the cache must be rebuilt.
-  // Otherwise, return the cached data and skip the rest of the function.
+  // Retrieve the projects from storage, if present.
+  $projects = update_project_storage('update_project_data');
+  // If $projects is empty, then the data must be rebuilt.
+  // Otherwise, return the data and skip the rest of the function.
   if (!empty($projects)) {
     return $projects;
   }
@@ -359,8 +357,8 @@ function update_calculate_project_data($available) {
   // projects or releases).
   drupal_alter('update_status', $projects);
 
-  // Cache the site's update status for at most 1 hour.
-  _update_cache_set('update_project_data', $projects, REQUEST_TIME + 3600);
+  // Store the site's update status for at most 1 hour.
+  update_storage()->setWithExpire('update_project_data', $projects, 3600);
   return $projects;
 }
 
@@ -750,37 +748,36 @@ function update_calculate_project_update_status(&$project_data, $available) {
 }
 
 /**
- * Retrieves data from {cache_update} or empties the cache when necessary.
+ * Retrieves update storage data or empties it.
  *
  * Two very expensive arrays computed by this module are the list of all
  * installed modules and themes (and .info data, project associations, etc), and
  * the current status of the site relative to the currently available releases.
- * These two arrays are cached in the {cache_update} table and used whenever
- * possible. The cache is cleared whenever the administrator visits the status
- * report, available updates report, or the module or theme administration
- * pages, since we should always recompute the most current values on any of
- * those pages.
+ * These two arrays are stored and used whenever possible. The data is cleared
+ * whenever the administrator visits the status report, available updates
+ * report, or the module or theme administration pages, since we should always
+ * recompute the most current values on any of those pages.
  *
  * Note: while both of these arrays are expensive to compute (in terms of disk
  * I/O and some fairly heavy CPU processing), neither of these is the actual
  * data about available updates that we have to fetch over the network from
- * updates.drupal.org. That information is stored with the
- * 'update_available_releases' cache ID -- it needs to persist longer than 1
+ * updates.drupal.org. That information is stored in the
+ * 'update_available_releases' collection -- it needs to persist longer than 1
  * hour and never get invalidated just by visiting a page on the site.
  *
- * @param $cid
- *   The cache ID of data to return from the cache. Valid options are
- *   'update_project_data' and 'update_project_projects'.
+ * @param $key
+ *   The key of data to return. Valid options are 'update_project_data' and
+ *   'update_project_projects'.
  *
  * @return
- *   The cached value of the $projects array generated by
+ *   The stored value of the $projects array generated by
  *   update_calculate_project_data() or update_get_projects(), or an empty array
- *   when the cache is cleared.
+ *   when the storage is cleared.
  */
-function update_project_cache($cid) {
+function update_project_storage($key) {
   $projects = array();
 
-  // On certain paths, we should clear the cache and recompute the projects for
+  // On certain paths, we should clear the data and recompute the projects for
   // update status of the site to avoid presenting stale information.
   $paths = array(
     'admin/modules',
@@ -794,13 +791,10 @@ function update_project_cache($cid) {
     'admin/reports/updates/check',
   );
   if (in_array(current_path(), $paths)) {
-    _update_cache_clear($cid);
+    update_storage()->delete($key);
   }
   else {
-    $cache = _update_cache_get($cid);
-    if (!empty($cache->data) && $cache->expire > REQUEST_TIME) {
-      $projects = $cache->data;
-    }
+    $projects = update_storage()->get($key);
   }
   return $projects;
 }
diff --git a/core/modules/update/update.fetch.inc b/core/modules/update/update.fetch.inc
index a4d1bd7..61bc80f 100644
--- a/core/modules/update/update.fetch.inc
+++ b/core/modules/update/update.fetch.inc
@@ -117,8 +117,8 @@ function _update_fetch_data() {
 /**
  * Processes a task to fetch available update data for a single project.
  *
- * Once the release history XML data is downloaded, it is parsed and saved into
- * the {cache_update} table in an entry just for that project.
+ * Once the release history XML data is downloaded, it is parsed and saved in an
+ * entry just for that project.
  *
  * @param $project
  *   Associative array of information about the project to fetch data for.
@@ -132,13 +132,11 @@ function _update_process_fetch_task($project) {
   $fail = &drupal_static(__FUNCTION__, array());
   // This can be in the middle of a long-running batch, so REQUEST_TIME won't
   // necessarily be valid.
-  $now = time();
+  $request_time_difference = time() - REQUEST_TIME;
   if (empty($fail)) {
     // If we have valid data about release history XML servers that we have
-    // failed to fetch from on previous attempts, load that from the cache.
-    if (($cache = _update_cache_get('fetch_failures')) && ($cache->expire > $now)) {
-      $fail = $cache->data;
-    }
+    // failed to fetch from on previous attempts, load that.
+    $fail = update_storage()->get('fetch_failures');
   }
 
   $max_fetch_attempts = $update_config->get('fetch.max_attempts');
@@ -179,43 +177,43 @@ function _update_process_fetch_task($project) {
   }
 
   $frequency = $update_config->get('check.interval_days');
-  $cid = 'available_releases::' . $project_name;
-  _update_cache_set($cid, $available, $now + (60 * 60 * 24 * $frequency));
+  $available['last_fetch'] = REQUEST_TIME + $request_time_difference;
+  update_storage('update_available_releases')->setWithExpire($project_name, $available, $request_time_difference + (60 * 60 * 24 * $frequency));
 
   // Stash the $fail data back in the DB for the next 5 minutes.
-  _update_cache_set('fetch_failures', $fail, $now + (60 * 5));
+  update_storage()->setWithExpire('fetch_failures', $fail, $request_time_difference + (60 * 5));
 
   // Whether this worked or not, we did just (try to) check for updates.
-  variable_set('update_last_check', $now);
+  variable_set('update_last_check', REQUEST_TIME + $request_time_difference);
 
   // Now that we processed the fetch task for this project, clear out the
-  // record in {cache_update} for this task so we're willing to fetch again.
-  _update_cache_clear('fetch_task::' . $project_name);
+  // record for this task so we're willing to fetch again.
+  update_storage('update_fetch_task')->delete($project_name);
 
   return $success;
 }
 
 /**
- * Clears out all the cached available update data and initiates re-fetching.
+ * Clears out all the available update data and initiates re-fetching.
  */
 function _update_refresh() {
   module_load_include('inc', 'update', 'update.compare');
 
   // Since we're fetching new available update data, we want to clear
-  // our cache of both the projects we care about, and the current update
-  // status of the site. We do *not* want to clear the cache of available
+  // both the projects we care about, and the current update
+  // status of the site. We do *not* want to clear the data of available
   // releases just yet, since that data (even if it's stale) can be useful
   // during update_get_projects(); for example, to modules that implement
   // hook_system_info_alter() such as cvs_deploy.
-  _update_cache_clear('update_project_projects');
-  _update_cache_clear('update_project_data');
+  update_storage()->delete('update_project_projects');
+  update_storage()->delete('update_project_data');
 
   $projects = update_get_projects();
 
-  // Now that we have the list of projects, we should also clear our cache of
-  // available release data, since even if we fail to fetch new data, we need
+  // Now that we have the list of projects, we should also clear the available
+  // release data, since even if we fail to fetch new data, we need
   // to clear out the stale data at this point.
-  _update_cache_clear('available_releases::', TRUE);
+  update_storage('available_releases')->deleteAll();
 
   foreach ($projects as $key => $project) {
     update_create_fetch_task($project);
@@ -226,8 +224,7 @@ function _update_refresh() {
  * Adds a task to the queue for fetching release history data for a project.
  *
  * We only create a new fetch task if there's no task already in the queue for
- * this particular project (based on 'fetch_task::' entries in the
- * {cache_update} table).
+ * this particular project (based on 'update_fetch_task' key-value collection).
  *
  * @param $project
  *   Associative array of information about a project as created by
@@ -243,29 +240,13 @@ function _update_refresh() {
 function _update_create_fetch_task($project) {
   $fetch_tasks = &drupal_static(__FUNCTION__, array());
   if (empty($fetch_tasks)) {
-    $fetch_tasks = _update_get_cache_multiple('fetch_task');
+    $fetch_tasks = update_storage('update_fetch_task')->getAll();
   }
-  $cid = 'fetch_task::' . $project['name'];
-  if (empty($fetch_tasks[$cid])) {
+  if (empty($fetch_tasks[$project['name']])) {
     $queue = queue('update_fetch_tasks');
     $queue->createItem($project);
-    // Due to race conditions, it is possible that another process already
-    // inserted a row into the {cache_update} table and the following query will
-    // throw an exception.
-    // @todo: Remove the need for the manual check by relying on a queue that
-    // enforces unique items.
-    try {
-      db_insert('cache_update')
-        ->fields(array(
-          'cid' => $cid,
-          'created' => REQUEST_TIME,
-        ))
-        ->execute();
-    }
-    catch (Exception $e) {
-      // The exception can be ignored safely.
-    }
-    $fetch_tasks[$cid] = REQUEST_TIME;
+    update_storage('update_fetch_task')->set($project['name'], $project);
+    $fetch_tasks[$project['name']] = REQUEST_TIME;
   }
 }
 
diff --git a/core/modules/update/update.install b/core/modules/update/update.install
index 14efc3a..8eedda1 100644
--- a/core/modules/update/update.install
+++ b/core/modules/update/update.install
@@ -57,15 +57,6 @@ function update_requirements($phase) {
 }
 
 /**
- * Implements hook_schema().
- */
-function update_schema() {
-  $schema['cache_update'] = drupal_get_schema_unprocessed('system', 'cache');
-  $schema['cache_update']['description'] = 'Cache table for the Update module to store information about available releases, fetched from central server.';
-  return $schema;
-}
-
-/**
  * Implements hook_install().
  */
 function update_install() {
@@ -162,3 +153,10 @@ function update_update_8000() {
     'update_notification_threshold' => 'notification.threshold',
   ));
 }
+
+/**
+ * Delete the {cache_update} table.
+ */
+function update_update_8001() {
+  db_delete('cache_update');
+}
diff --git a/core/modules/update/update.module b/core/modules/update/update.module
index 51e77e6..053f2e6 100644
--- a/core/modules/update/update.module
+++ b/core/modules/update/update.module
@@ -1,5 +1,9 @@
 <?php
 
+use Drupal\Core\Database\Database;
+use Drupal\Core\KeyValueStore\DatabaseStorage;
+use Drupal\Core\KeyValueStore\DatabaseStorageExpirable;
+
 /**
  * @file
  * Handles updates of Drupal core and contributed projects.
@@ -287,7 +291,7 @@ function update_cron() {
   $interval = 60 * 60 * 24 * $frequency;
   if ((REQUEST_TIME - variable_get('update_last_check', 0)) > $interval) {
     // If the configured update interval has elapsed, we want to invalidate
-    // the cached data for all projects, attempt to re-fetch, and trigger any
+    // the data for all projects, attempt to re-fetch, and trigger any
     // configured notifications about the new status.
     update_refresh();
     update_fetch_data();
@@ -311,33 +315,33 @@ function update_cron() {
 /**
  * Implements hook_themes_enabled().
  *
- * If themes are enabled, we invalidate the cache of available updates.
+ * If themes are enabled, we invalidate the information of available updates.
  */
 function update_themes_enabled($themes) {
-  // Clear all update module caches.
-  _update_cache_clear();
+  // Clear all update module data.
+  update_storage_clear();
 }
 
 /**
  * Implements hook_themes_disabled().
  *
- * If themes are disabled, we invalidate the cache of available updates.
+ * If themes are disabled, we invalidate the information of available updates.
  */
 function update_themes_disabled($themes) {
-  // Clear all update module caches.
-  _update_cache_clear();
+  // Clear all update module data.
+  update_storage_clear();
 }
 
 /**
  * Implements hook_form_FORM_ID_alter() for system_modules().
  *
  * Adds a form submission handler to the system modules form, so that if a site
- * admin saves the form, we invalidate the cache of available updates.
+ * admin saves the form, we invalidate the information of available updates.
  *
  * @see _update_cache_clear()
  */
 function update_form_system_modules_alter(&$form, $form_state) {
-  $form['#submit'][] = 'update_cache_clear_submit';
+  $form['#submit'][] = 'update_storage_clear_submit';
 }
 
 /**
@@ -345,9 +349,9 @@ function update_form_system_modules_alter(&$form, $form_state) {
  *
  * @see update_form_system_modules_alter()
  */
-function update_cache_clear_submit($form, &$form_state) {
-  // Clear all update module caches.
-  _update_cache_clear();
+function update_storage_clear_submit($form, &$form_state) {
+  // Clear all update module data.
+  update_storage_clear();
 }
 
 /**
@@ -362,9 +366,9 @@ function _update_no_data() {
 }
 
 /**
- * Tries to get update information from cache and refreshes it when necessary.
+ * Tries to get update information and refreshes it when necessary.
  *
- * In addition to checking the cache lifetime, this function also ensures that
+ * In addition to checking the lifetime, this function also ensures that
  * there are no .info files for enabled modules or themes that have a newer
  * modification timestamp than the last time we checked for available update
  * data. If any .info file was modified, it almost certainly means a new version
@@ -373,8 +377,8 @@ function _update_no_data() {
  * results.
  *
  * @param $refresh
- *   (optional) Boolean to indicate if this method should refresh the cache
- *   automatically if there's no data. Defaults to FALSE.
+ *   (optional) Boolean to indicate if this method should refresh automatically
+ *   if there's no data. Defaults to FALSE.
  *
  * @return
  *   Array of data about available releases, keyed by project shortname.
@@ -386,9 +390,8 @@ function update_get_available($refresh = FALSE) {
   module_load_include('inc', 'update', 'update.compare');
   $needs_refresh = FALSE;
 
-  // Grab whatever data we currently have cached in the DB.
-  $available = _update_get_cached_available_releases();
-  $num_avail = count($available);
+  // Grab whatever data we currently have.
+  $available = update_storage('update_available_releases')->getAll();
 
   $projects = update_get_projects();
   foreach ($projects as $key => $project) {
@@ -426,8 +429,8 @@ function update_get_available($refresh = FALSE) {
     // Attempt to drain the queue of fetch tasks.
     update_fetch_data();
     // After processing the queue, we've (hopefully) got better data, so pull
-    // the latest from the cache again and use that directly.
-    $available = _update_get_cached_available_releases();
+    // the latest data again and use that directly.
+    $available = update_storage('update_available_releases')->getAll();
   }
 
   return $available;
@@ -468,29 +471,6 @@ function update_fetch_data() {
 }
 
 /**
- * Returns all currently cached data about available releases for all projects.
- *
- * @return
- *   Array of data about available releases, keyed by project shortname.
- */
-function _update_get_cached_available_releases() {
-  $data = array();
-  $cache_items = _update_get_cache_multiple('available_releases');
-  foreach ($cache_items as $cid => $cache) {
-    $cache->data['last_fetch'] = $cache->created;
-    if ($cache->expire < REQUEST_TIME) {
-      $cache->data['fetch_status'] = UPDATE_FETCH_PENDING;
-    }
-    // The project shortname is embedded in the cache ID, even if there's no
-    // data for this project in the DB at all, so use that for the indexes in
-    // the array.
-    $parts = explode('::', $cid, 2);
-    $data[$parts[1]] = $cache->data;
-  }
-  return $data;
-}
-
-/**
  * Implements hook_mail().
  *
  * Constructs the e-mail notification message when the site is out of date.
@@ -725,137 +705,30 @@ function update_verify_update_archive($project, $archive_file, $directory) {
 }
 
 /**
- * @defgroup update_status_cache Private update status cache system
- * @{
- * Functions to manage the update status cache.
- *
- * We specifically do NOT use the core cache API for saving the fetched data
- * about available updates. It is vitally important that this cache is only
- * cleared when we're populating it after successfully fetching new available
- * update data. Usage of the core cache API results in all sorts of potential
- * problems that would result in attempting to fetch available update data all
- * the time, including if a site has a "minimum cache lifetime" (which is both a
- * minimum and a maximum) defined, or if a site uses memcache or another
- * pluggable cache system that assumes volatile caches.
- *
- * The Update Manager module still uses the {cache_update} table, but instead of
- * using the cache API, there are private helper functions that implement these
- * same basic tasks but ensure that the cache is not prematurely cleared, and
- * that the data is always stored in the database, even if memcache or another
- * cache backend is in use.
- */
-
-/**
- * Stores data in the private update status cache table.
  *
- * @param $cid
- *   The cache ID to save the data with.
- * @param $data
- *   The data to store.
- * @param $expire
- *   One of the following values:
- *   - CacheBackendInterface::CACHE_PERMANENT: Indicates that the item should
- *     never be removed except by explicitly using _update_cache_clear().
- *   - A Unix timestamp: Indicates that the item should be kept at least until
- *     the given time, after which it will be invalidated.
- *
- * @see _update_cache_get()
+ * @return Drupal\Core\KeyValueStore\KeyValueStoreExpirableInterface
  */
-function _update_cache_set($cid, $data, $expire) {
-  $fields = array(
-    'created' => REQUEST_TIME,
-    'expire' => $expire,
-  );
-  if (!is_string($data)) {
-    $fields['data'] = serialize($data);
-    $fields['serialized'] = 1;
-  }
-  else {
-    $fields['data'] = $data;
-    $fields['serialized'] = 0;
-  }
-  db_merge('cache_update')
-    ->key(array('cid' => $cid))
-    ->fields($fields)
-    ->execute();
-}
-
-/**
- * Retrieves data from the private update status cache table.
- *
- * @param $cid
- *   The cache ID to retrieve.
- *
- * @return
- *   An array of data for the given cache ID, or NULL if the ID was not found.
- *
- * @see _update_cache_set()
- */
-function _update_cache_get($cid) {
-  $cache = db_query("SELECT data, created, expire, serialized FROM {cache_update} WHERE cid = :cid", array(':cid' => $cid))->fetchObject();
-  if (isset($cache->data)) {
-    if ($cache->serialized) {
-      $cache->data = unserialize($cache->data);
+function update_storage($collection = 'update') {
+  $storage = &drupal_static(__FUNCTION__);
+  if (!isset($storage[$collection])) {
+    // @todo Set without expiration currently does not work on
+    //   DatabaseStorageExpirable.
+    if ($collection == 'update_fetch_task') {
+      $storage[$collection] = new DatabaseStorage($collection, array('connection' => Database::getConnection()));
     }
-  }
-  return $cache;
-}
-
-/**
- * Returns an array of cache items with a given cache ID prefix.
- *
- * @param string $cid_prefix
- *   The cache ID prefix.
- *
- * @return
- *   Associative array of cache items, keyed by cache ID.
- */
-function _update_get_cache_multiple($cid_prefix) {
-  $data = array();
-  $result = db_select('cache_update')
-    ->fields('cache_update', array('cid', 'data', 'created', 'expire', 'serialized'))
-    ->condition('cache_update.cid', $cid_prefix . '::%', 'LIKE')
-    ->execute();
-  foreach ($result as $cache) {
-    if ($cache) {
-      if ($cache->serialized) {
-        $cache->data = unserialize($cache->data);
-      }
-      $data[$cache->cid] = $cache;
+    else {
+      $storage[$collection] = new DatabaseStorageExpirable($collection, array('connection' => Database::getConnection()));
     }
   }
-  return $data;
+  return $storage[$collection];
 }
 
 /**
- * Invalidates cached data relating to update status.
- *
- * @param $cid
- *   (optional) Cache ID of the record to clear from the private update module
- *   cache. If empty, all records will be cleared from the table except fetch
- *   tasks. Defaults to NULL.
- * @param $wildcard
- *   (optional) If TRUE, cache IDs starting with $cid are deleted in addition to
- *   the exact cache ID specified by $cid. Defaults to FALSE.
+ * Invalidates stored data relating to update status.
  */
-function _update_cache_clear($cid = NULL, $wildcard = FALSE) {
-  if (empty($cid)) {
-    db_delete('cache_update')
-      // Clear everything except fetch task information because these are used
-      // to ensure that the fetch task queue items are not added multiple times.
-      ->condition('cid', 'fetch_task::%', 'NOT LIKE')
-      ->execute();
-  }
-  else {
-    $query = db_delete('cache_update');
-    if ($wildcard) {
-      $query->condition('cid', $cid . '%', 'LIKE');
-    }
-    else {
-      $query->condition('cid', $cid);
-    }
-    $query->execute();
-  }
+function update_storage_clear() {
+  update_storage()->deleteAll();
+  update_storage('update_available_release')->deleteAll();
 }
 
 /**
@@ -864,8 +737,8 @@ function _update_cache_clear($cid = NULL, $wildcard = FALSE) {
  * Called from update.php (among others) to flush the caches. Since we're
  * running update.php, we are likely to install a new version of something, in
  * which case, we want to check for available update data again. However,
- * because we have our own caching system, we need to directly clear the
- * the database table ourselves at this point and return nothing.
+ * because we use the key value storage system, we need to clear directly at
+ * this point and return nothing.
  *
  * However, we only want to do this from update.php, since otherwise, we'd lose
  * all the available update data on every cron run. So, we specifically check if
@@ -874,16 +747,12 @@ function _update_cache_clear($cid = NULL, $wildcard = FALSE) {
  */
 function update_cache_flush() {
   if (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE == 'update') {
-    _update_cache_clear();
+    update_storage_clear();
   }
   return array();
 }
 
 /**
- * @} End of "defgroup update_status_cache".
- */
-
-/**
  * Returns a short unique identifier for this Drupal installation.
  *
  * @return
diff --git a/core/modules/update/update.settings.inc b/core/modules/update/update.settings.inc
index 0a5e337..442510b 100644
--- a/core/modules/update/update.settings.inc
+++ b/core/modules/update/update.settings.inc
@@ -92,7 +92,7 @@ function update_settings_validate($form, &$form_state) {
 /**
  * Form submission handler for update_settings().
  *
- * Also invalidates the cache of available updates if the "Check for updates of
+ * Also invalidates the data of available updates if the "Check for updates of
  * disabled modules and themes" setting is being changed. The available updates
  * report needs to refetch available update data after this setting changes or
  * it would show misleading things (e.g., listing the disabled projects on the
@@ -104,9 +104,9 @@ function update_settings_submit($form, $form_state) {
   $config = config('update.settings');
 
   // See if the update_check_disabled setting is being changed, and if so,
-  // invalidate all cached update status data.
+  // invalidate all update status data.
   if ($form_state['values']['update_check_disabled'] != $config->get('check.disabled_extensions')) {
-    _update_cache_clear();
+    update_storage_clear();
   }
 
   $config
diff --git a/core/modules/user/lib/Drupal/user/KeyValueStoreWithOwner.php b/core/modules/user/lib/Drupal/user/KeyValueStoreWithOwner.php
new file mode 100644
index 0000000..24478c9
--- /dev/null
+++ b/core/modules/user/lib/Drupal/user/KeyValueStoreWithOwner.php
@@ -0,0 +1,155 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\user\KeyValueStoreWithOwner.
+ */
+
+namespace Drupal\user;
+
+use Drupal\Core\KeyValueStore\KeyValueStoreExpirableInterface;
+use Drupal\Core\Lock\LockBackendInterface;
+
+/**
+ * Stores and retrieves values from a key/value store with a default key.
+ */
+class KeyValueStoreWithOwner {
+
+  /**
+   * The key/value storage object used for this data.
+   *
+   * @var Drupal\Core\KeyValueStore\KeyValueStoreExpireInterface;
+   */
+  protected $storage;
+
+  /**
+   * The lock object used for this data.
+   *
+   * @var Drupal\Core\Lock\LockBackendInterface
+   */
+  protected $lockBackend;
+
+  /**
+   * The owner key to store along with the data.
+   *
+   * @var mixed
+   */
+  protected $owner;
+
+  /**
+   * The time to live for items in seconds. Defaults to a week.
+   *
+   * @var int
+   */
+  protected $expire = 604800;
+
+  /**
+   * Constructs a new object for accessing data from a key/value store.
+   *
+   * @param KeyValueStoreExpireInterface $storage
+   *   The key/value storage object used for this data.
+   * @param Drupal\Core\Lock\LockBackendInterface $lockBackend
+   *   The lock object used for this data.
+   * @param mixed $owner
+   *   The owner key to store along with the data.
+   */
+  function __construct(KeyValueStoreExpirableInterface $storage, LockBackendInterface $lockBackend, $owner) {
+    $this->storage = $storage;
+    $this->lockBackend = $lockBackend;
+    $this->owner = $owner;
+  }
+
+  /**
+   * Returns the stored value for the default key.
+   *
+   * @param string $key
+   *   The key of the data to retrieve.
+   *
+   * @return mixed
+   *   The data to retieve, or NULL if the key does not exist.
+   */
+  function get($key) {
+    if ($object = $this->storage->get($key)) {
+      return $object->data;
+    }
+  }
+
+  /**
+   * Adds the value for the default key if it doesn't exist yet.
+   *
+   * @param string $key
+   *   The key of the data to check and store.
+   * @param mixed $value
+   *   The data to store.
+   *
+   * @return bool
+   *   TRUE if the data was set, FALSE if it already existed.
+   */
+  function setIfNotExists($key, $value) {
+    $value = (object) array(
+      'owner' => $this->owner,
+      'data' => $value,
+      'updated' => REQUEST_TIME,
+    );
+    return $this->storage->setWithExpireIfNotExists($key, $value, $this->expire);
+  }
+
+  /**
+   * Sets the value for the default key.
+   *
+   * @param string $key
+   *   The key of the data to store.
+   * @param mixed $value
+   *   The data to store.
+   */
+  function set($key, $value) {
+    if ($this->lockBackend->acquire($key)) {
+      $object = $this->storage->get($key);
+      if (!$object || $object->owner == $this->owner) {
+        $value = (object) array(
+          'owner' => $this->owner,
+          'data' => $value,
+          'updated' => REQUEST_TIME,
+        );
+        $this->storage->setWithExpire($key, $value, $this->expire);
+      }
+      $this->lockBackend->release($key);
+    }
+  }
+
+  /**
+   * Gets the metadata for a key.
+   *
+   * @param string $key
+   *   The key of the data to store.
+   *
+   * @return mixed
+   *   An object with the owner and updated time if the key has a value, NULL
+   *   otherwise.
+   */
+  function getMetadata($key) {
+    $object = $this->storage->get($key);
+    if ($object) {
+      unset($object->data);
+      return $object;
+    }
+  }
+
+  /**
+   * Deletes the value of the default key.
+   *
+   * @param string $key
+   *   The key of the data to store.
+   */
+  function delete($key) {
+    if (!$this->lockBackend->acquire($key)) {
+      $this->lockBackend->wait($key);
+      if (!$this->lockBackend->acquire($key)) {
+        throw new KeyValueStoreWithOwnerException("Couldn't acquire lock");
+      }
+    }
+    $this->storage->delete($key);
+    $this->lockBackend->release($key);
+  }
+
+}
diff --git a/core/modules/user/lib/Drupal/user/KeyValueStoreWithOwnerException.php b/core/modules/user/lib/Drupal/user/KeyValueStoreWithOwnerException.php
new file mode 100644
index 0000000..4a35e23
--- /dev/null
+++ b/core/modules/user/lib/Drupal/user/KeyValueStoreWithOwnerException.php
@@ -0,0 +1,13 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\Core\KeyValueStore\KeyValueStoreDefaultException.
+ */
+
+namespace Drupal\user;
+
+/**
+ * Exception thrown when KeyValueStoreWithOwner can not acquire a lock.
+ */
+class KeyValueStoreWithOwnerException extends \Exception {}
diff --git a/core/modules/user/lib/Drupal/user/KeyValueStoreWithOwnerFactory.php b/core/modules/user/lib/Drupal/user/KeyValueStoreWithOwnerFactory.php
new file mode 100644
index 0000000..dc389ba
--- /dev/null
+++ b/core/modules/user/lib/Drupal/user/KeyValueStoreWithOwnerFactory.php
@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\user\KeyValueStoreWithOwnerFactory.
+ */
+
+namespace Drupal\user;
+
+use Drupal\Core\Database\Connection;
+use Drupal\Core\KeyValueStore\DatabaseStorageExpirable;
+use Drupal\Core\Lock\LockBackendInterface;
+
+/**
+ * Provides a factory for key/value storage that needs an owner.
+ */
+class KeyValueStoreWithOwnerFactory {
+
+  /**
+   * The connection object used for this data.
+   *
+   * @var Drupal\Core\Database\Connection $connection
+   */
+  protected $connection;
+
+  /**
+   * The lock object used for this data.
+   *
+   * @var Drupal\Core\Lock\LockBackendInterface $lockBackend
+   */
+  protected $lockBackend;
+
+  /**
+   * Constructs a Drupal\user\KeyValueStoreWithOwnerFactory object.
+   *
+   * @param Drupal\Core\Database\Connection $connection
+   *   The connection object used for this data.
+   * @param Drupal\Core\Lock\LockBackendInterface $lockBackend
+   *   The lock object used for this data.
+   */
+  function __construct(Connection $connection, LockBackendInterface $lockBackend) {
+    $this->connection = $connection;
+    $this->lockBackend = $lockBackend;
+  }
+
+  /**
+   * Creates a Drupal\user\KeyValueStoreWithOwner stored in the database.
+   *
+   * @param string $namespace
+   *   The namespace to use for this key/value store.
+   *
+   * @return Drupal\user\KeyValueStoreWithOwner
+   *   An instance of the the key/value store.
+   */
+  function get($namespace) {
+    $storage = new DatabaseStorageExpirable($namespace, array('connection' => $this->connection));
+    return new KeyValueStoreWithOwner($storage, $this->lockBackend, $GLOBALS['user']->uid ?: session_id());
+  }
+
+}
diff --git a/core/modules/user/lib/Drupal/user/Tests/TempStoreDatabaseTest.php b/core/modules/user/lib/Drupal/user/Tests/TempStoreDatabaseTest.php
new file mode 100644
index 0000000..4927ffa
--- /dev/null
+++ b/core/modules/user/lib/Drupal/user/Tests/TempStoreDatabaseTest.php
@@ -0,0 +1,165 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\user\Tests\TempStoreDatabaseTest.
+ */
+
+namespace Drupal\user\Tests;
+
+use Drupal\simpletest\UnitTestBase;
+use Drupal\user\KeyValueStoreWithOwnerFactory;
+use Drupal\Core\Lock\DatabaseLockBackend;
+use Drupal\Core\Database\Database;
+use stdClass;
+
+/**
+ * Tests the TempStore namespace.
+ *
+ * @see Drupal\Core\TempStore\TempStore.
+ */
+class TempStoreDatabaseTest extends UnitTestBase {
+
+  /**
+   * A key/value store factory.
+   *
+   * @var Drupal\user\KeyValueStoreWithOwnerFactory
+   */
+  protected $storeFactory;
+
+  /**
+   * The name of the collection to set and retrieve.
+   *
+   * @var string
+   */
+  protected $collection;
+
+  /**
+   * An array of (fake) user ids.
+   *
+   * @var array
+   */
+  protected $users = array();
+
+  /**
+   * An array of random stdClass objects.
+   *
+   * @var array
+   */
+  protected $objects = array();
+
+  public static function getInfo() {
+    return array(
+      'name' => 'TempStore',
+      'description' => 'Tests the temporary object storage system.',
+      'group' => 'TempStore',
+    );
+  }
+
+  protected function setUp() {
+    parent::setUp();
+    module_load_install('system');
+    $schema = system_schema();
+    db_create_table('semaphore', $schema['semaphore']);
+    db_create_table('key_value_expire', $schema['key_value_expire']);
+    $this->storeFactory = new KeyValueStoreWithOwnerFactory(Database::getConnection(), new DatabaseLockBackend());
+    $this->collection = $this->randomName();
+
+    // Create two users and two objects for testing.
+    for ($i = 0; $i <= 3; $i++) {
+      $this->objects[$i] = $this->randomObject();
+      $this->users[$i] = mt_rand(500, 5000000);
+    }
+  }
+
+  /**
+   * Generates a random PHP object.
+   *
+   * @param int $size
+   *   The number of random keys to add to the object.
+   *
+   * @return stdClass
+   *   The generated object, with the specified number of random keys. Each key
+   *   has a random string value.
+   */
+  public function randomObject($size = 4) {
+    $object = new stdClass();
+    for ($i = 0; $i < $size; $i++) {
+      $random_key = $this->randomName();
+      $random_value = $this->randomString();
+      $object->{$random_key} = $random_value;
+    }
+    return $object;
+  }
+
+  /**
+   * Tests the UserTempStore API.
+   */
+  public function testUserTempStore() {
+    $key = $this->randomName();
+    // First test that only one setIfNotExists succeeds.
+    for ($i = 0; $i <= 1; $i++) {
+      $store = $this->getStorePerUid($this->users[$i]);
+      // Setting twice results only in the first succeeding.
+      $this->assertEqual(!$i, $store->setIfNotExists($key, $this->objects[$i]));
+      $metadata = $store->getMetadata($key);
+      $this->assertEqual($this->users[0], $metadata->owner);
+      $this->assertIdenticalObject($this->objects[0], $store->get($key));
+    }
+    // Remove the item.
+    $store->delete($key);
+    // Try to set it again.
+    $store->setIfNotExists($key, $this->objects[1]);
+    // This time it succeeds.
+    $this->assertIdenticalObject($this->objects[1], $store->get($key));
+    // This user can update the object.
+    $store->set($key, $this->objects[2]);
+    $this->assertIdenticalObject($this->objects[2], $store->get($key));
+    // But another can't.
+    $store = $this->getStorePerUid($this->users[2]);
+    $store->set($key, $this->objects[3]);
+    $this->assertIdenticalObject($this->objects[2], $store->get($key));
+    // Now manually expire the item (this is not exposed by the API) and then
+    // assert it is no longer accessible.
+    db_update('key_value_expire')
+      ->fields(array('expire' => REQUEST_TIME - 1))
+      ->condition('collection', $this->collection)
+      ->condition('name', $key)
+      ->execute();
+    $this->assertFalse($store->get($key));
+  }
+
+  /**
+   * Returns a KeyValueStoreWithOwner belonging to the passed in user.
+   *
+   * @param int $uid
+   *   A user ID.
+   *
+   * @return Drupal\user\KeyValueStoreWithOwner
+   *   The key/value store object.
+   */
+  protected function getStorePerUid($uid) {
+    $GLOBALS['user']->uid = $uid;
+    // This relies on the logged user uid!!
+    return $this->storeFactory->get($this->collection);
+  }
+
+  /**
+   * Checks to see if two objects are identical.
+   *
+   * @param object $object1
+   *   The first object to check.
+   * @param object $object2
+   *   The second object to check.
+   */
+  protected function assertIdenticalObject($object1, $object2) {
+    $identical = TRUE;
+    foreach ($object1 as $key => $value) {
+      $identical = $identical && isset($object2->$key) && $object2->$key === $value;
+    }
+    $this->assertTrue($identical, format_string('!object1 is identical to !object2', array(
+      '!object1' => var_export($object1, TRUE),
+      '!object2' => var_export($object2, TRUE),
+    )));
+  }
+}
diff --git a/modules/README.txt b/modules/README.txt
index f4e35b5..339aa00 100644
--- a/modules/README.txt
+++ b/modules/README.txt
@@ -1,4 +1,18 @@
+Place downloaded and custom modules that extend your site functionality beyond
+Drupal core in this directory to ensure clean separation from core modules and
+to facilitate safe, self-contained code updates. Contributed modules from the
+Drupal community may be downloaded at http://drupal.org/project/modules.
 
-This directory should be used to place downloaded and custom modules
-which are common to all sites. This will allow you to more easily
-update Drupal core files.
+It is safe to organize modules into subdirectories, such as "contrib" for
+contributed modules, and "custom" for custom modules. Note that if you move a
+module to a subdirectory after it has been enabled, you may need to clear the
+Drupal cache so that it can be found.
+
+In multisite configuration, modules found in this directory are available to
+all sites. In addition to this directory, shared common modules may also be kept
+in the sites/all/modules directory and will take precedence over modules in this
+directory. Alternatively, the sites/your_site_name/modules directory pattern may
+be used to restrict modules to a specific site instance.
+
+Refer to the "Developing for Drupal" section of the README.txt in the Drupal
+root directory for further information on extending Drupal with custom modules.
diff --git a/profiles/README.txt b/profiles/README.txt
index 2bbf4c9..69bb492 100644
--- a/profiles/README.txt
+++ b/profiles/README.txt
@@ -1,4 +1,18 @@
+Place downloaded and custom installation profiles in this directory to ensure
+separation from Drupal core profiles and to facilitate safe, self-contained code
+updates.
 
-This directory should be used to place downloaded and custom profiles
-which are common to all sites. This will allow you to more easily
-update Drupal core files.
+In multisite configuration, installation profiles found in this directory are
+available to all sites during their initial site installation. Shared common
+profiles may also be kept in the sites/all/profiles directory and will take
+precedence over profiles in this directory. Alternatively, the
+sites/your_site_name/profiles directory pattern may be used to restrict a
+profile's availability to a specific site instance.
+
+Additionally, modules and themes may be placed inside subdirectories in a
+specific installation profile such as profiles/your_site_profile/modules and
+profiles/your_site_profile/themes respectively to restrict their usage to only
+sites that were installed with that specific profile.
+
+Refer to the "Installation Profiles" section of the README.txt in the Drupal
+root directory for further information.
diff --git a/sites/README.txt b/sites/README.txt
new file mode 100644
index 0000000..0372902
--- /dev/null
+++ b/sites/README.txt
@@ -0,0 +1,10 @@
+This directory structure contains the settings and configuration files specific
+to your site or sites and is an integral part of multisite configurations.
+
+It is now recommended to place your custom and downloaded extensions in the
+/modules, /themes, and /profiles directories located in the Drupal root. The
+sites/all/ subdirectory structure, which was recommended in previous versions
+of Drupal, is still supported.
+
+See core/INSTALL.txt for information about single-site installation or
+multisite configuration.
diff --git a/themes/README.txt b/themes/README.txt
index e942521..320b967 100644
--- a/themes/README.txt
+++ b/themes/README.txt
@@ -1,4 +1,16 @@
+Place downloaded and custom themes that modify your site's appearance in this
+directory to ensure clean separation from Drupal core and to facilitate safe,
+self-contained code updates. Contributed themes from the Drupal community may
+be downloaded at http://drupal.org/project/themes.
 
-This directory should be used to place downloaded and custom themes
-which are common to all sites. This will allow you to more easily
-update Drupal core files.
+It is safe to organize themes into subdirectories and is recommended to use
+Drupal's sub-theme functionality to ensure easy maintenance and upgrades.
+
+In multisite configuration, themes found in this directory are available to
+all sites. In addition to this directory, shared common themes may also be kept
+in the sites/all/themes directory and will take precedence over themes in this
+directory. Alternatively, the sites/your_site_name/themes directory pattern may
+be used to restrict themes to a specific site instance.
+
+Refer to the "Appearance" section of the README.txt in the Drupal root
+directory for further information on theming.