diff --git a/core/lib/Drupal/Core/Session/AccountInterface.php b/core/lib/Drupal/Core/Session/AccountInterface.php
index 1dbc13c..2de00de 100644
--- a/core/lib/Drupal/Core/Session/AccountInterface.php
+++ b/core/lib/Drupal/Core/Session/AccountInterface.php
@@ -32,6 +32,17 @@ public function id();
   public function getRoles();
 
   /**
+   * Whether a user has a certain permission.
+   *
+   * @param string $permission
+   *   The permission string to check.
+   *
+   * @return bool
+   *   TRUE if the user has the permission, FALSE otherwise.
+   */
+  public function hasPermission($permission);
+
+  /**
    * Returns the session ID.
    *
    * @return string|NULL
diff --git a/core/lib/Drupal/Core/Session/UserSession.php b/core/lib/Drupal/Core/Session/UserSession.php
index 300cd8f..59604f5 100644
--- a/core/lib/Drupal/Core/Session/UserSession.php
+++ b/core/lib/Drupal/Core/Session/UserSession.php
@@ -94,6 +94,25 @@ public function getRoles() {
   /**
    * {@inheritdoc}
    */
+  public function hasPermission($permission) {
+    // User #1 has all privileges.
+    if ((int) $this->id() === 1) {
+      return TRUE;
+    }
+
+    $roles = user_role_permissions($this->getRoles());
+    foreach ($roles as $permissions) {
+      if (isset($permissions[$permission])) {
+        return TRUE;
+      }
+    }
+
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function getSecureSessionId() {
     return $this->ssid;
   }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
index b613121..cf677ce 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
@@ -11,6 +11,7 @@
 use Drupal\Core\Database\Database;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\DrupalKernel;
+use Drupal\Core\Session\UserSession;
 use Drupal\simpletest\WebTestBase;
 use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
 use Symfony\Component\HttpFoundation\Request;
@@ -144,15 +145,12 @@ protected function setUp() {
     // Ensure that the session is not written to the new environment and replace
     // the global $user session with uid 1 from the new test site.
     drupal_save_session(FALSE);
-    // Login as uid 1.
-    $user = db_query('SELECT * FROM {users} WHERE uid = :uid', array(':uid' => 1))->fetchObject();
-    // Load roles for the user object.
-    $roles = array(DRUPAL_AUTHENTICATED_RID => DRUPAL_AUTHENTICATED_RID);
-    $result = db_query('SELECT rid, uid FROM {users_roles} WHERE uid = :uid', array(':uid' => 1));
-    foreach ($result as $record) {
-      $roles[$record->rid] = $record->rid;
-    }
-    $user->roles = $roles;
+    // Load values for uid 1.
+    $values = db_query('SELECT * FROM {users} WHERE uid = :uid', array(':uid' => 1))->fetchAssoc();
+    // Load rolest.
+    $values['roles'] = array_merge(array(DRUPAL_AUTHENTICATED_RID), db_query('SELECT rid FROM {users_roles} WHERE uid = :uid', array(':uid' => 1))->fetchCol());
+    // Create a new user session object.
+    $user = new UserSession($values);
 
     // Generate and set a D8-compatible session cookie.
     $this->prepareD8Session();
diff --git a/core/modules/user/lib/Drupal/user/Plugin/Core/Entity/User.php b/core/modules/user/lib/Drupal/user/Plugin/Core/Entity/User.php
index 0f2e28a..deef744 100644
--- a/core/modules/user/lib/Drupal/user/Plugin/Core/Entity/User.php
+++ b/core/modules/user/lib/Drupal/user/Plugin/Core/Entity/User.php
@@ -180,7 +180,7 @@ class User extends EntityNG implements UserInterface {
    */
   public $roles;
 
-    /**
+  /**
    * The plain data values of the contained properties.
    *
    * Define default values.
@@ -387,4 +387,23 @@ public function removeRole($rid) {
     $this->set('roles', array_diff($this->getRoles(), array($rid)));
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function hasPermission($permission) {
+    // User #1 has all privileges.
+    if ((int) $this->id() === 1) {
+      return TRUE;
+    }
+
+    $roles = user_role_permissions($this->getRoles());
+    foreach ($roles as $permissions) {
+      if (isset($permissions[$permission])) {
+        return TRUE;
+      }
+    }
+
+    return FALSE;
+  }
+
 }
diff --git a/core/modules/user/lib/Drupal/user/RoleStorageController.php b/core/modules/user/lib/Drupal/user/RoleStorageController.php
index 4b6ca87..de2e983 100644
--- a/core/modules/user/lib/Drupal/user/RoleStorageController.php
+++ b/core/modules/user/lib/Drupal/user/RoleStorageController.php
@@ -21,7 +21,6 @@ public function resetCache(array $ids = NULL) {
     parent::resetCache($ids);
 
     // Clear the user access cache.
-    drupal_static_reset('user_access');
     drupal_static_reset('user_role_permissions');
   }
 
diff --git a/core/modules/user/lib/Drupal/user/Tests/UserPermissionsTest.php b/core/modules/user/lib/Drupal/user/Tests/UserPermissionsTest.php
index 3fc3b4b..5752def 100644
--- a/core/modules/user/lib/Drupal/user/Tests/UserPermissionsTest.php
+++ b/core/modules/user/lib/Drupal/user/Tests/UserPermissionsTest.php
@@ -46,7 +46,6 @@ function testUserPermissionChanges() {
     $edit[$rid . '[administer nodes]'] = TRUE;
     $this->drupalPost('admin/people/permissions', $edit, t('Save permissions'));
     $this->assertText(t('The changes have been saved.'), 'Successful save message displayed.');
-    drupal_static_reset('user_access');
     drupal_static_reset('user_role_permissions');
     $this->assertTrue(user_access('administer nodes', $account), 'User now has "administer nodes" permission.');
 
@@ -56,7 +55,6 @@ function testUserPermissionChanges() {
     $edit[$rid . '[access user profiles]'] = FALSE;
     $this->drupalPost('admin/people/permissions', $edit, t('Save permissions'));
     $this->assertText(t('The changes have been saved.'), 'Successful save message displayed.');
-    drupal_static_reset('user_access');
     drupal_static_reset('user_role_permissions');
     $this->assertFalse(user_access('access user profiles', $account), 'User no longer has "access user profiles" permission.');
   }
diff --git a/core/modules/user/lib/Drupal/user/UserBCDecorator.php b/core/modules/user/lib/Drupal/user/UserBCDecorator.php
index eed508b..82b3908 100644
--- a/core/modules/user/lib/Drupal/user/UserBCDecorator.php
+++ b/core/modules/user/lib/Drupal/user/UserBCDecorator.php
@@ -76,4 +76,10 @@ public function removeRole($rid) {
     $this->decorated->removeRole($rid);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function hasPermission($permission) {
+    return $this->decorated->hasPermission($permission);
+  }
 }
diff --git a/core/modules/user/lib/Drupal/user/UserInterface.php b/core/modules/user/lib/Drupal/user/UserInterface.php
index 4dc1481..25a3de0 100644
--- a/core/modules/user/lib/Drupal/user/UserInterface.php
+++ b/core/modules/user/lib/Drupal/user/UserInterface.php
@@ -50,4 +50,15 @@ public function addRole($rid);
    */
   public function removeRole($rid);
 
+  /**
+   * Whether a user has a certain permission.
+   *
+   * @param string $permission
+   *   The permission string to check.
+   *
+   * @return bool
+   *   TRUE if the user has the permission, FALSE otherwise.
+   */
+  public function hasPermission($permission);
+
 }
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index e0ef6e6..c0dbd7e 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -475,30 +475,7 @@ function user_access($string, AccountInterface $account = NULL) {
   // Make sure we are working with the BC decorator.
   $account = $account instanceof User ? $account->getBCEntity() : $account;
 
-  // User #1 has all privileges:
-  if ($account->uid == 1) {
-    return TRUE;
-  }
-
-  // To reduce the number of SQL queries, we cache the user's permissions
-  // in a static variable.
-  // Use the advanced drupal_static() pattern, since this is called very often.
-  static $drupal_static_fast;
-  if (!isset($drupal_static_fast)) {
-    $drupal_static_fast['perm'] = &drupal_static(__FUNCTION__);
-  }
-  $perm = &$drupal_static_fast['perm'];
-  if (!isset($perm[$account->uid])) {
-    $role_permissions = user_role_permissions($account->getRoles());
-
-    $perms = array();
-    foreach ($role_permissions as $one_role) {
-      $perms += $one_role;
-    }
-    $perm[$account->uid] = $perms;
-  }
-
-  return isset($perm[$account->uid][$string]);
+  return $account->hasPermission($string);
 }
 
 /**
@@ -1961,7 +1938,6 @@ function user_role_grant_permissions($rid, array $permissions = array()) {
   }
 
   // Clear the user access cache.
-  drupal_static_reset('user_access');
   drupal_static_reset('user_role_permissions');
 }
 
@@ -1984,7 +1960,6 @@ function user_role_revoke_permissions($rid, array $permissions = array()) {
     ->execute();
 
   // Clear the user access cache.
-  drupal_static_reset('user_access');
   drupal_static_reset('user_role_permissions');
 }