diff --git a/core/lib/Drupal/Core/Config/Config.php b/core/lib/Drupal/Core/Config/Config.php
index 584feb7c53..adefeeea54 100644
--- a/core/lib/Drupal/Core/Config/Config.php
+++ b/core/lib/Drupal/Core/Config/Config.php
@@ -85,19 +85,7 @@ public function get($key = '') {
     if (!isset($this->overriddenData)) {
       $this->setOverriddenData();
     }
-    if (empty($key)) {
-      return $this->overriddenData;
-    }
-    else {
-      $parts = explode('.', $key);
-      if (count($parts) == 1) {
-        return isset($this->overriddenData[$key]) ? $this->overriddenData[$key] : NULL;
-      }
-      else {
-        $value = NestedArray::getValue($this->overriddenData, $parts, $key_exists);
-        return $key_exists ? $value : NULL;
-      }
-    }
+    return NestedArray::getValue($this->overriddenData, $key ? explode('.', $key) : []);
   }
 
   /**
@@ -141,6 +129,24 @@ public function setModuleOverride(array $data) {
     return $this;
   }
 
+  /**
+   * Returns overrides applied to this configuration object.
+   *
+   * Simply comparing the the data from getOriginal() with and without overrides
+   * does not help to detect overrides if the override happens to have the same
+   * value as the original data.
+   *
+   * @param string $key
+   *   A string that maps to a key within the configuration data.
+   *
+   * @return mixed
+   *   The value of the override or empty if not overwritten.
+   */
+  public function getOverrides($key = '') {
+    $overrides = $this->mergeOverridesWithData([]);
+    return NestedArray::getValue($overrides, $key ? explode('.', $key) : []);
+  }
+
   /**
    * Sets the current data for this configuration object.
    *
@@ -153,13 +159,7 @@ public function setModuleOverride(array $data) {
    *   The configuration object.
    */
   protected function setOverriddenData() {
-    $this->overriddenData = $this->data;
-    if (isset($this->moduleOverrides) && is_array($this->moduleOverrides)) {
-      $this->overriddenData = NestedArray::mergeDeepArray([$this->overriddenData, $this->moduleOverrides], TRUE);
-    }
-    if (isset($this->settingsOverrides) && is_array($this->settingsOverrides)) {
-      $this->overriddenData = NestedArray::mergeDeepArray([$this->overriddenData, $this->settingsOverrides], TRUE);
-    }
+    $this->overriddenData = $this->mergeOverridesWithData($this->data);
     return $this;
   }
 
@@ -280,27 +280,28 @@ public function getOriginal($key = '', $apply_overrides = TRUE) {
     $original_data = $this->originalData;
     if ($apply_overrides) {
       // Apply overrides.
-      if (isset($this->moduleOverrides) && is_array($this->moduleOverrides)) {
-        $original_data = NestedArray::mergeDeepArray([$original_data, $this->moduleOverrides], TRUE);
-      }
-      if (isset($this->settingsOverrides) && is_array($this->settingsOverrides)) {
-        $original_data = NestedArray::mergeDeepArray([$original_data, $this->settingsOverrides], TRUE);
-      }
+      $original_data = $this->mergeOverridesWithData($original_data);
     }
+    return NestedArray::getValue($original_data, $key ? explode('.', $key) : []);
+  }
 
-    if (empty($key)) {
-      return $original_data;
+  /**
+   * Merge module and settings overrides with the provided data.
+   *
+   * @param array $data
+   *   The data to merge the overrides with.
+   *
+   * @return array
+   *   The overridden data, unchanged if no overrides apply.
+   */
+  protected function mergeOverridesWithData(array $data) {
+    if (isset($this->moduleOverrides) && is_array($this->moduleOverrides)) {
+      $data = NestedArray::mergeDeepArray([$data, $this->moduleOverrides], TRUE);
     }
-    else {
-      $parts = explode('.', $key);
-      if (count($parts) == 1) {
-        return isset($original_data[$key]) ? $original_data[$key] : NULL;
-      }
-      else {
-        $value = NestedArray::getValue($original_data, $parts, $key_exists);
-        return $key_exists ? $value : NULL;
-      }
+    if (isset($this->settingsOverrides) && is_array($this->settingsOverrides)) {
+      $data = NestedArray::mergeDeepArray([$data, $this->settingsOverrides], TRUE);
     }
+    return $data;
   }
 
 }
diff --git a/core/lib/Drupal/Core/Config/ConfigBase.php b/core/lib/Drupal/Core/Config/ConfigBase.php
index 4f445ea21c..bb8149642a 100644
--- a/core/lib/Drupal/Core/Config/ConfigBase.php
+++ b/core/lib/Drupal/Core/Config/ConfigBase.php
@@ -129,19 +129,7 @@ public static function validateName($name) {
    *   The data that was requested.
    */
   public function get($key = '') {
-    if (empty($key)) {
-      return $this->data;
-    }
-    else {
-      $parts = explode('.', $key);
-      if (count($parts) == 1) {
-        return isset($this->data[$key]) ? $this->data[$key] : NULL;
-      }
-      else {
-        $value = NestedArray::getValue($this->data, $parts, $key_exists);
-        return $key_exists ? $value : NULL;
-      }
-    }
+    return NestedArray::getValue($this->data, $key ? explode('.', $key) : []);
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Core/Config/ConfigTest.php b/core/tests/Drupal/Tests/Core/Config/ConfigTest.php
index 41c3e93c99..9e3b136672 100644
--- a/core/tests/Drupal/Tests/Core/Config/ConfigTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/ConfigTest.php
@@ -173,6 +173,7 @@ public function testSaveExisting($data) {
    * @covers ::setModuleOverride
    * @covers ::setSettingsOverride
    * @covers ::getOriginal
+   * @covers ::getOverrides
    * @dataProvider overrideDataProvider
    */
   public function testOverrideData($data, $module_data, $setting_data) {
@@ -184,26 +185,38 @@ public function testOverrideData($data, $module_data, $setting_data) {
 
     // Save so that the original data is stored.
     $this->config->save();
+    $this->assertEquals([], $this->config->getOverrides());
 
     // Set module override data and check value before and after save.
     $this->config->setModuleOverride($module_data);
     $this->assertConfigDataEquals($module_data);
+    $this->assertEquals($module_data, $this->config->getOverrides());
     $this->config->save();
     $this->assertConfigDataEquals($module_data);
+    $this->assertEquals($module_data, $this->config->getOverrides());
+
+    // Reset the module overrides.
+    $this->config->setModuleOverride([]);
+    $this->assertEquals([], $this->config->getOverrides());
 
     // Set setting override data and check value before and after save.
     $this->config->setSettingsOverride($setting_data);
     $this->assertConfigDataEquals($setting_data);
+    $this->assertEquals($setting_data, $this->config->getOverrides());
     $this->config->save();
     $this->assertConfigDataEquals($setting_data);
+    $this->assertEquals($setting_data, $this->config->getOverrides());
 
     // Set module overrides again to ensure override order is correct.
     $this->config->setModuleOverride($module_data);
+    $merged_overrides = array_merge($module_data, $setting_data);
 
     // Setting data should be overriding module data.
     $this->assertConfigDataEquals($setting_data);
+    $this->assertEquals($merged_overrides, $this->config->getOverrides());
     $this->config->save();
     $this->assertConfigDataEquals($setting_data);
+    $this->assertEquals($merged_overrides, $this->config->getOverrides());
 
     // Check original data has not changed.
     $this->assertOriginalConfigDataEquals($data, FALSE);
@@ -215,7 +228,29 @@ public function testOverrideData($data, $module_data, $setting_data) {
     foreach ($setting_data as $key => $value) {
       $config_value = $this->config->getOriginal($key);
       $this->assertEquals($value, $config_value);
+      $this->assertEquals($value, $this->config->getOverrides($key));
     }
+
+    // Check that getOverrides only returns overrides.
+    foreach ($data as $key => $value) {
+      $config_value = $this->config->get($key);
+      if (isset($merged_overrides[$key])) {
+        $this->assertEquals($config_value, $this->config->getOverrides($key));
+      }
+      else {
+        $this->assertNull($this->config->getOverrides($key));
+        $this->assertEquals($value, $config_value);
+      }
+    }
+
+    // Check that the overrides can be completely reset.
+    $this->config->setModuleOverride([]);
+    $this->config->setSettingsOverride([]);
+    $this->assertConfigDataEquals($data);
+    $this->assertEquals([], $this->config->getOverrides());
+    $this->config->save();
+    $this->assertConfigDataEquals($data);
+    $this->assertEquals([], $this->config->getOverrides());
   }
 
   /**
@@ -449,6 +484,37 @@ public function overrideDataProvider() {
           'a' => 'settingValue',
         ],
       ],
+      [
+        // Original data.
+        [
+          'a' => 'originalValue',
+          'b' => 'originalValue',
+          'c' => 'originalValue',
+        ],
+        // Module overrides.
+        [
+          'a' => 'moduleValue',
+          'b' => 'moduleValue',
+        ],
+        // Setting overrides.
+        [
+          'a' => 'settingValue',
+        ],
+      ],
+      [
+        // Original data.
+        [
+          'a' => 'allTheSameValue',
+        ],
+        // Module overrides.
+        [
+          'a' => 'allTheSameValue',
+        ],
+        // Setting overrides.
+        [
+          'a' => 'allTheSameValue',
+        ],
+      ],
     ];
   }