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
@@ -638,4 +638,17 @@
   }
 
+  /**
+   * Gets the raw data without overrides.
+   *
+   * @return array
+   *   The raw data.
+   */
+  public function getRawData() {
+    if (!$this->isLoaded) {
+      $this->load();
+    }
+    return $this->data;
+  }
+
 }
 
diff -u b/core/lib/Drupal/Core/Config/ConfigFactory.php b/core/lib/Drupal/Core/Config/ConfigFactory.php
--- b/core/lib/Drupal/Core/Config/ConfigFactory.php
+++ b/core/lib/Drupal/Core/Config/ConfigFactory.php
@@ -443,11 +443,13 @@
    *   The configuration event.
    */
   public function onConfigSave(ConfigEvent $event) {
-    // Clear out any other cache keys apart from the config object being saved.
+    // Ensure that the static cache contains up to date configuration objects by
+    // replacing the data on any entries for the configuration object apart
+    // from the one that references the actual config object being saved.
     $saved_config = $event->getConfig();
     foreach ($this->getCacheKeys($saved_config->getName()) as $cache_key) {
       if ($this->cache[$cache_key] != $saved_config) {
-        unset($this->cache[$cache_key]);
+        $this->cache[$cache_key]->setData($saved_config->getRawData());
       }
     }
   }
diff -u b/core/modules/config/lib/Drupal/config/Tests/ConfigOverrideTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigOverrideTest.php
--- b/core/modules/config/lib/Drupal/config/Tests/ConfigOverrideTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigOverrideTest.php
@@ -124,9 +124,19 @@
     $this->assertTrue($config->isNew(), 'The configuration object config_test.new is new');
     $this->assertIdentical($config->get('key'), 'override');
     \Drupal::configFactory()->disableOverrides();
-    $config = \Drupal::config('config_test.new');
-    $this->assertIdentical($config->get('key'), NULL);
+    $config_raw = \Drupal::config('config_test.new');
+    $this->assertIdentical($config_raw->get('key'), NULL);
+    $config_raw
+      ->set('key', 'raw')
+      ->set('new_key', 'new_value')
+      ->save();
     \Drupal::configFactory()->enableOverrides();
+    // Ensure override is preserved but all other data has been updated
+    // accordingly.
+    $this->assertIdentical($config->get('key'), 'override');
+    $this->assertIdentical($config->get('new_key'), 'new_value');
+    $raw_data = $config->getRawData();
+    $this->assertIdentical($raw_data['key'], 'raw');
   }
 
 }