diff -u b/core/lib/Drupal/Core/Config/Config.php b/core/lib/Drupal/Core/Config/Config.php
--- b/core/lib/Drupal/Core/Config/Config.php
+++ b/core/lib/Drupal/Core/Config/Config.php
@@ -50,14 +50,7 @@
   protected $data;
 
   /**
-   * The overridden data of the configuration object.
-   *
-   * @var array
-   */
-  protected $overrides = array();
-
-  /**
-   * The current runtime data ($data + $overrides).
+   * The current runtime data ($data + $overrides from Config Context).
    *
    * @var array
    */
@@ -275,10 +268,8 @@
    *   The configuration object.
    */
   public function setOverride(array $data) {
-    if ($this->context->allowOverrides()) {
-      $this->overrides = NestedArray::mergeDeepArray(array($this->overrides, $data), TRUE);
-      $this->resetOverriddenData();
-    }
+    $this->context->setOverrides($this->getName(), $data);
+    $this->resetOverriddenData();
     return $this;
   }
 
@@ -292,8 +283,9 @@
    */
   protected function setOverriddenData() {
     $this->overriddenData = $this->data;
-    if (!empty($this->overrides)) {
-      $this->overriddenData = NestedArray::mergeDeepArray(array($this->overriddenData, $this->overrides), TRUE);
+    $overrides = $this->context->getOverrides($this->getName());
+    if (is_array($overrides)) {
+      $this->overriddenData = NestedArray::mergeDeepArray(array($this->overriddenData, $overrides), TRUE);
     }
     return $this;
   }
diff -u b/core/lib/Drupal/Core/Config/Context/ConfigContext.php b/core/lib/Drupal/Core/Config/Context/ConfigContext.php
--- b/core/lib/Drupal/Core/Config/Context/ConfigContext.php
+++ b/core/lib/Drupal/Core/Config/Context/ConfigContext.php
@@ -9,6 +9,7 @@
 
 use Drupal\Core\Config\Config;
 use Drupal\Core\Config\ConfigEvent;
+use Drupal\Component\Utility\NestedArray;
 use Drupal\Component\Uuid\Uuid;
 use Symfony\Component\EventDispatcher\EventDispatcher;
 
@@ -30,2 +31,9 @@
   /**
+   * Any config overrides of key-value pairs.
+   *
+   * @var array
+   */
+  protected $overrides = array();
+
+  /**
    * An event dispatcher instance to use for configuration events.
@@ -42,13 +50,6 @@
   protected $uuid;
 
   /**
-   * Allow overrides to apply in this context.
-   *
-   * @var bool
-   */
-  protected $allowOverrides = TRUE;
-
-  /**
    * Constructs the configuration context.
    *
    * @param \Symfony\Component\EventDispatcher\EventDispatcher $event_dispatcher
@@ -105,10 +106,25 @@
   }
 
   /**
-   * Implements \Drupal\Core\Config\Context\ContextInterface::allowOverrides().
+   * Implements Drupal\Core\Config\Context\ContextInterface::setOverride().
+   */
+  public function setOverrides($config_name, $data) {
+    if (!isset($this->overrides[$config_name])) {
+      $this->overrides[$config_name] = $data;
+    }
+    else {
+      $this->overrides[$config_name] = NestedArray::mergeDeepArray(array($this->overrides[$config_name], $data), TRUE);
+    }
+  }
+
+  /**
+   * Implements Drupal\Core\Config\Context\ContextInterface::getOverrides().
    */
-  public function allowOverrides() {
-    return $this->allowOverrides;
+  public function getOverrides($config_name) {
+    if (isset($this->overrides[$config_name])) {
+      return $this->overrides[$config_name];
+    }
+    return FALSE;
   }
 
 }
diff -u b/core/lib/Drupal/Core/Config/Context/ContextInterface.php b/core/lib/Drupal/Core/Config/Context/ContextInterface.php
--- b/core/lib/Drupal/Core/Config/Context/ContextInterface.php
+++ b/core/lib/Drupal/Core/Config/Context/ContextInterface.php
@@ -79,10 +79,23 @@
 
   /**
-   * Returns whether this context allows overrides.
+   * Sets the override data for a configuration object.
    *
-   * @return bool
-   *   TRUE if overrides are allowed, FALSE otherwise.
+   * @param string $config_name
+   *   Configuration name.
+   * @param array data
+   *   The override data.
    */
-  public function allowOverrides();
+  public function setOverrides($config_name, $data);
+
+  /**
+   * Gets the override data for a configuration object.
+   *
+   * @param string $config_name
+   *   Configuration name.
+   *
+   * @return mixed
+   *   The override data or FALSE if there is none.
+   */
+  public function getOverrides($config_name);
 
 }
diff -u b/core/lib/Drupal/Core/Config/Context/FreeConfigContext.php b/core/lib/Drupal/Core/Config/Context/FreeConfigContext.php
--- b/core/lib/Drupal/Core/Config/Context/FreeConfigContext.php
+++ b/core/lib/Drupal/Core/Config/Context/FreeConfigContext.php
@@ -14,7 +14,17 @@
 
   /**
-   * Overrides are not allowed in this context.
+   * Implements Drupal\Core\Config\Context\ContextInterface::getOverrides().
    */
-  protected $allowOverrides = FALSE;
+  public function getOverrides($config_name) {
+    // Do nothing as this is override free.
+    return FALSE;
+  }
+
+  /**
+   * Implements Drupal\Core\Config\Context\ContextInterface::setOverride().
+   */
+  public function setOverrides($config_name, $data) {
+    // Do nothing as this is override free.
+  }
 
 }