diff --git a/core/lib/Drupal/Core/Config/Config.php b/core/lib/Drupal/Core/Config/Config.php
index 0337d28..5da2a7e 100644
--- a/core/lib/Drupal/Core/Config/Config.php
+++ b/core/lib/Drupal/Core/Config/Config.php
@@ -275,8 +275,10 @@ protected function replaceData(array $data) {
    *   The configuration object.
    */
   public function setOverride(array $data) {
-    $this->overrides = NestedArray::mergeDeepArray(array($this->overrides, $data), TRUE);
-    $this->resetOverriddenData();
+    if ($this->context->allowOverrides()) {
+      $this->overrides = NestedArray::mergeDeepArray(array($this->overrides, $data), TRUE);
+      $this->resetOverriddenData();
+    }
     return $this;
   }
 
diff --git a/core/lib/Drupal/Core/Config/ConfigFactory.php b/core/lib/Drupal/Core/Config/ConfigFactory.php
index 4edbead..0cd0382 100644
--- a/core/lib/Drupal/Core/Config/ConfigFactory.php
+++ b/core/lib/Drupal/Core/Config/ConfigFactory.php
@@ -140,7 +140,8 @@ public function rename($old_name, $new_name) {
    *   The config factory object.
    */
   public function enterContext(ContextInterface $context) {
-    $this->contextStack[] = $context;
+    // Initialize the context as it is being entered.
+    $this->contextStack[] = $context->init();
     return $this;
   }
 
diff --git a/core/lib/Drupal/Core/Config/Context/ConfigContext.php b/core/lib/Drupal/Core/Config/Context/ConfigContext.php
index 9be0f71..306c049 100644
--- a/core/lib/Drupal/Core/Config/Context/ConfigContext.php
+++ b/core/lib/Drupal/Core/Config/Context/ConfigContext.php
@@ -15,18 +15,12 @@
 /**
  * Defines the base configuration context object.
  *
- * A configuration context object provides a data array that can be used:
- *   - as a parameter to get customized configuration objects.
- *   - as a store of config data used to override values.
+ * A configuration context object provides a data array that can be used
+ * as parameters to get customized configuration objects.
  */
 class ConfigContext implements ContextInterface {
 
   /**
-   * Predefined key, values to override specific configuration objects.
-   */
-  const OVERRIDE = 'config.override';
-
-  /**
    * The actual storage of key-value pairs.
    *
    * @var array
@@ -48,6 +42,13 @@ class ConfigContext implements ContextInterface {
   protected $uuid;
 
   /**
+   * Allow overrides to apply in this context.
+   *
+   * @var boolean
+   */
+  protected $allowOverrides = TRUE;
+
+  /**
    * Constructs the configuration context.
    *
    * @param \Symfony\Component\EventDispatcher\EventDispatcher $event_dispatcher
@@ -60,10 +61,7 @@ public function __construct(EventDispatcher $event_dispatcher) {
   /**
    * Implements Drupal\Core\Config\Context\ContextInterface::init().
    */
-  public function init($context_key, $data) {
-    if ($data) {
-      $this->set($context_key, $data);
-    }
+  public function init() {
     $this->setUuid();
     // Notify event listeners that a configuration context has been created.
     $this->notify('context', NULL);
@@ -85,20 +83,6 @@ public function set($key, $value) {
   }
 
   /**
-   * Sets override data.
-   *
-   * @param mixed $data
-   *   Override data to store.
-   *
-   * @return \Drupal\Core\Config\Context\ConfigContext
-   *   The config context object.
-   */
-  public function setOverride($data) {
-    $this->init(self::OVERRIDE, $data);
-    return $this;
-  }
-
-  /**
    * Implements Drupal\Core\Config\Context\ContextInterface::setUuid().
    */
   public function setUuid() {
@@ -120,4 +104,11 @@ public function notify($config_event_name, Config $config = NULL) {
     $this->eventDispatcher->dispatch('config.' . $config_event_name, new ConfigEvent($this, $config));
   }
 
+  /**
+   * Implements Drupal\Core\Config\Context\ContextInterface::allowOverrides().
+   */
+  public function allowOverrides() {
+    return $this->allowOverrides;
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Config/Context/ContextInterface.php b/core/lib/Drupal/Core/Config/Context/ContextInterface.php
index b3107a7..3d16dcd 100644
--- a/core/lib/Drupal/Core/Config/Context/ContextInterface.php
+++ b/core/lib/Drupal/Core/Config/Context/ContextInterface.php
@@ -22,21 +22,13 @@
  */
 interface ContextInterface {
 
-  /*
+  /**
    * Initialises a config context for use.
    *
-   * Creates a unique context identifier, adds data and notifies system about
-   * the new context.
-   *
-   * @param string $context_key
-   *   The key that is used to set context data.
-   * @param mixed $data
-   *   The context config data.
-   *
    * @return \Drupal\Core\Config\Context\ConfigContext
    *   The config context object.
    */
-  public function init($context_key, $data);
+  public function init();
 
   /**
    * Returns the stored value for a given key.
@@ -85,4 +77,12 @@ public function getUuid();
    */
   public function notify($config_event_name, Config $config = NULL);
 
+  /**
+   * Whether this context allows overrides.
+   *
+   * @return boolean
+   *   TRUE if overrides are allowed, FALSE otherwise.
+   */
+  public function allowOverrides();
+
 }
diff --git a/core/lib/Drupal/Core/Config/Context/FreeConfigContext.php b/core/lib/Drupal/Core/Config/Context/FreeConfigContext.php
new file mode 100644
index 0000000..ae8061f
--- /dev/null
+++ b/core/lib/Drupal/Core/Config/Context/FreeConfigContext.php
@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Config\Context\FreeConfigContext.
+ */
+
+namespace Drupal\Core\Config\Context;
+
+/**
+ * Defines the override-free configuration context object.
+ */
+class FreeConfigContext extends ConfigContext {
+
+  /**
+   * Overrides are not allowed in this context.
+   */
+  protected $allowOverrides = FALSE;
+}
diff --git a/core/lib/Drupal/Core/Config/Context/GlobalConfigContext.php b/core/lib/Drupal/Core/Config/Context/GlobalConfigContext.php
deleted file mode 100644
index 9e8fa1e..0000000
--- a/core/lib/Drupal/Core/Config/Context/GlobalConfigContext.php
+++ /dev/null
@@ -1,29 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Config\Context\GlobalConfigContext.
- */
-
-namespace Drupal\Core\Config\Context;
-
-/**
- * Defines the global configuration context object.
- *
- * The global configuration context allows config object data to be overridden
- * with values from the $conf global.
- */
-class GlobalConfigContext extends ConfigContext {
-
-  /**
-   * Sets global override data.
-   *
-   * @return \Drupal\Core\Config\Context\ConfigContext
-   *   The config context object.
-   */
-  public function setGlobalOverride() {
-    global $conf;
-    $this->init(self::OVERRIDE, $conf);
-    return $this;
-  }
-}
diff --git a/core/lib/Drupal/Core/CoreBundle.php b/core/lib/Drupal/Core/CoreBundle.php
index 6f7ff31..8c68ae4 100644
--- a/core/lib/Drupal/Core/CoreBundle.php
+++ b/core/lib/Drupal/Core/CoreBundle.php
@@ -58,15 +58,14 @@ public function build(ContainerBuilder $container) {
     $container->register('config.context', 'Drupal\Core\Config\Context\ContextInterface')
       ->setFactoryService(new Reference('config.context.factory'))
       ->setFactoryMethod('get')
-      ->addArgument('Drupal\Core\Config\Context\GlobalConfigContext')
-      ->addTag('persist')
-      ->addMethodCall('setGlobalOverride');
+      ->addTag('persist');
 
     // Register a config context with no overrides for use in administration
     // forms, enabling modules and importing configuration.
     $container->register('config.context.free', 'Drupal\Core\Config\Context\ContextInterface')
       ->setFactoryService(new Reference('config.context.factory'))
-      ->setFactoryMethod('get');
+      ->setFactoryMethod('get')
+      ->addArgument('Drupal\Core\Config\Context\FreeConfigContext');
 
     $container->register('config.factory', 'Drupal\Core\Config\ConfigFactory')
       ->addArgument(new Reference('config.storage'))
@@ -278,7 +277,7 @@ public function build(ContainerBuilder $container) {
     $container->register('request_close_subscriber', 'Drupal\Core\EventSubscriber\RequestCloseSubscriber')
       ->addArgument(new Reference('module_handler'))
       ->addTag('event_subscriber');
-    $container->register('config_global_override_subscriber', 'Drupal\Core\EventSubscriber\ConfigOverrideSubscriber')
+    $container->register('config_global_override_subscriber', 'Drupal\Core\EventSubscriber\ConfigGlobalOverrideSubscriber')
       ->addTag('event_subscriber');
     $container->register('language_request_subscriber', 'Drupal\Core\EventSubscriber\LanguageRequestSubscriber')
       ->addArgument(new Reference('language_manager'))
diff --git a/core/lib/Drupal/Core/EventSubscriber/ConfigGlobalOverrideSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/ConfigGlobalOverrideSubscriber.php
new file mode 100644
index 0000000..b2aa76e
--- /dev/null
+++ b/core/lib/Drupal/Core/EventSubscriber/ConfigGlobalOverrideSubscriber.php
@@ -0,0 +1,40 @@
+<?php
+/**
+ * @file
+ * Contains \Drupal\Core\EventSubscriber\ConfigGlobalOverrideSubscriber.
+ */
+
+namespace Drupal\Core\EventSubscriber;
+
+use Drupal\Core\Config\Config;
+use Drupal\Core\Config\ConfigEvent;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Override configuration values with values in global $conf variable.
+ */
+class ConfigGlobalOverrideSubscriber implements EventSubscriberInterface {
+
+  /**
+   * Override configuration values with global $conf.
+   *
+   * @param \Drupal\Core\Config\ConfigEvent $event
+   *   The Event to process.
+   */
+  public function configInit(ConfigEvent $event) {
+    global $conf;
+
+    $config = $event->getConfig();
+    if (isset($conf[$config->getName()])) {
+      $config->setOverride($conf[$config->getName()]);
+    }
+  }
+
+  /**
+   * Implements EventSubscriberInterface::getSubscribedEvents().
+   */
+  static function getSubscribedEvents() {
+    $events['config.init'][] = array('configInit', 30);
+    return $events;
+  }
+}
diff --git a/core/lib/Drupal/Core/EventSubscriber/ConfigOverrideSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/ConfigOverrideSubscriber.php
deleted file mode 100644
index 376da10..0000000
--- a/core/lib/Drupal/Core/EventSubscriber/ConfigOverrideSubscriber.php
+++ /dev/null
@@ -1,41 +0,0 @@
-<?php
-/**
- * @file
- * Contains \Drupal\Core\EventSubscriber\ConfigOverrideSubscriber.
- */
-
-namespace Drupal\Core\EventSubscriber;
-
-use Drupal\Core\Config\Config;
-use Drupal\Core\Config\ConfigEvent;
-use Drupal\Core\Config\Context\ConfigContext;
-use Symfony\Component\EventDispatcher\EventSubscriberInterface;
-
-/**
- * Override configuration values with predefined values in context.
- */
-class ConfigOverrideSubscriber implements EventSubscriberInterface {
-
-  /**
-   * Overrides configuration values.
-   *
-   * @param \Drupal\Core\Config\ConfigEvent $event
-   *   The Event to process.
-   */
-  public function configInit(ConfigEvent $event) {
-    if ($override = $event->getContext()->get(ConfigContext::OVERRIDE)) {
-      $config = $event->getConfig();
-      if (isset($override[$config->getName()])) {
-        $config->setOverride($override[$config->getName()]);
-      }
-    }
-  }
-
-  /**
-   * Implements EventSubscriberInterface::getSubscribedEvents().
-   */
-  public static function getSubscribedEvents() {
-    $events['config.init'][] = array('configInit', 30);
-    return $events;
-  }
-}
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigLocaleOverride.php b/core/modules/config/lib/Drupal/config/Tests/ConfigLocaleOverride.php
index 78253d3..4377766 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigLocaleOverride.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigLocaleOverride.php
@@ -75,6 +75,12 @@ function testConfigLocaleUserOverride() {
       'langcode' => 'de',
     )));
 
+    // Ensure reading config without overrides results in expected data.
+    config_context_enter('config.context.free');
+    $config = config('config_test.system');
+    $this->assertIdentical($config->get('foo'), 'bar');
+    config_context_leave();
+
     $this->installSchema('user', 'users');
     $account = entity_create('user', array(
       'name' => 'French user',
@@ -83,15 +89,17 @@ function testConfigLocaleUserOverride() {
       'status' => 1,
       'preferred_langcode' => 'fr',
     ));
-    $config_factory = drupal_container()->get('config.factory');
 
-    $user_config_context = config_context_enter("Drupal\\user\\UserConfigContext");
+    $user_config_context = config_context_enter('Drupal\user\UserConfigContext');
     $user_config_context->setAccount($account);
     $config = config('config_test.system');
     $this->assertIdentical($config->get('foo'), 'fr bar');
 
     // Ensure that we get the expected value when we leave the user context.
-    $config_factory->leaveContext();
+    // The locale overrides contain an English override too, so although we
+    // are not in a user based language override context, the English
+    // language override applies due to the negotiated language for the page.
+    config_context_leave();
     $config = config('config_test.system');
     $this->assertIdentical($config->get('foo'), 'en bar');
 
@@ -103,6 +111,7 @@ function testConfigLocaleUserOverride() {
       'preferred_langcode' => 'de',
     ));
 
+    $config_factory = drupal_container()->get('config.factory');
     $config_factory->enterContext($user_config_context->setAccount($account));
     // Should not have to re-initialise config object to get new overrides as
     // the new context will have a different uuid.
@@ -118,7 +127,7 @@ function testConfigLocaleUserOverride() {
       'preferred_langcode' => 'en',
     ));
     // Create a new user config context to stack on top of the existign one.
-    $en_user_config_context = config_context_enter("Drupal\\user\\UserConfigContext");
+    $en_user_config_context = config_context_enter('Drupal\user\UserConfigContext');
     $en_user_config_context->setAccount($account);
     $config = config('config_test.system');
     $this->assertIdentical($config->get('foo'), 'en bar');
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigOverrideTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigOverrideTest.php
index 2fdf122..6dfcf4e 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigOverrideTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigOverrideTest.php
@@ -51,7 +51,6 @@ function testConfOverride() {
     $conf['config_test.system']['foo'] = 'overridden';
     $conf['config_test.system']['baz'] = 'injected';
     $conf['config_test.system']['404'] = 'derp';
-    drupal_container()->get('config.context')->setGlobalOverride();
 
     config_install_default_config('module', 'config_test');
 
@@ -63,31 +62,17 @@ function testConfOverride() {
     $this->assertFalse(isset($data['baz']));
     $this->assertIdentical($data['404'], $expected_original_data['404']);
 
-    // Remove the $conf overrides and reset value in config.context service.
-    unset($conf['config_test.system']);
-    drupal_container()->get('config.context')->setGlobalOverride();
-
-    // Verify that the original configuration data exists.
+    // Enter an override-free context to ensure the original data remains.
+    config_context_enter('config.context.free');
     $config = config('config_test.system');
     $this->assertIdentical($config->get('foo'), $expected_original_data['foo']);
     $this->assertIdentical($config->get('baz'), $expected_original_data['baz']);
     $this->assertIdentical($config->get('404'), $expected_original_data['404']);
+    config_context_leave();
 
-    // Apply the overridden data, that needs to be set into the config.context
-    // service.
-    $conf['config_test.system']['foo'] = 'overridden';
-    $conf['config_test.system']['baz'] = 'injected';
-    $conf['config_test.system']['404'] = 'derp';
-    drupal_container()->get('config.context')->setGlobalOverride();
-
-    // Verify that the in-memory configuration object still contains the
-    // original data.
-    $this->assertIdentical($config->get('foo'), $expected_original_data['foo']);
-    $this->assertIdentical($config->get('baz'), $expected_original_data['baz']);
-    $this->assertIdentical($config->get('404'), $expected_original_data['404']);
-
-    // Reload the configuration object.
-    $config->init();
+    // Get the configuration object in an overriden context (the one set by
+    // default).
+    $config = config('config_test.system');
 
     // Verify that it contains the overridden data from $conf.
     $this->assertIdentical($config->get('foo'), $conf['config_test.system']['foo']);
@@ -116,24 +101,15 @@ function testConfOverride() {
     $this->assertIdentical($config->get('baz'), $conf['config_test.system']['baz']);
     $this->assertIdentical($config->get('404'), $conf['config_test.system']['404']);
 
-    // Remove the $conf overrides and reset value in config.context service.
-    unset($conf['config_test.system']);
-    drupal_container()->get('config.context')->setGlobalOverride();
-
-    // Reload it and verify that it still contains the original data.
-    $config->init();
+    // Enter an override-free context to ensure the original data remains saved.
+    config_context_enter('config.context.free');
+    $config = config('config_test.system');
     $this->assertIdentical($config->get('foo'), $expected_original_data['foo']);
     $this->assertIdentical($config->get('baz'), $expected_original_data['baz']);
     $this->assertIdentical($config->get('404'), $expected_original_data['404']);
+    config_context_leave();
 
-    // Set globals before importing to prove that the imported file does not
-    // contain these values.
-    $conf['config_test.system']['foo'] = 'overridden';
-    $conf['config_test.system']['baz'] = 'injected';
-    $conf['config_test.system']['404'] = 'derp';
-
-    // Write file to staging
-    drupal_container()->get('config.context')->setGlobalOverride();
+    // Write file to staging.
     $staging = $this->container->get('config.storage.staging');
     $expected_new_data = array(
       'foo' => 'barbar',
@@ -152,6 +128,7 @@ function testConfOverride() {
     $this->assertIdentical($data['404'], $expected_new_data['404']);
 
     // Verifiy the overrides are still working.
+    $config = config('config_test.system');
     $this->assertIdentical($config->get('foo'), $conf['config_test.system']['foo']);
     $this->assertIdentical($config->get('baz'), $conf['config_test.system']['baz']);
     $this->assertIdentical($config->get('404'), $conf['config_test.system']['404']);
diff --git a/core/modules/user/lib/Drupal/user/UserConfigContext.php b/core/modules/user/lib/Drupal/user/UserConfigContext.php
index d6e4114..917787d 100644
--- a/core/modules/user/lib/Drupal/user/UserConfigContext.php
+++ b/core/modules/user/lib/Drupal/user/UserConfigContext.php
@@ -26,14 +26,6 @@ class UserConfigContext extends ConfigContext {
    */
   const USER_KEY = 'user.account';
 
-  /**
-   * Implements \Drupal\Core\Config\Context\ContextInterface::setUuid().
-   */
-  public function setUuid() {
-    // Use the user's uuid to identify the config context.
-    $this->uuid = $this->get(self::USER_KEY)->uuid();
-  }
-
   /*
    * Helper function to create config context for user accounts.
    *
@@ -44,7 +36,9 @@ public function setUuid() {
    *   The user config context object.
    */
   public function setAccount(User $account) {
-    $this->init(self::USER_KEY, $account);
+    $this->set(self::USER_KEY, $account);
+    // Re-initialize since the user change changes the context fundamentally.
+    $this->init();
     return $this;
   }