diff --git a/core/lib/Drupal/Core/Form/FormBuilder.php b/core/lib/Drupal/Core/Form/FormBuilder.php
index 4cd5c1c..8226c71 100644
--- a/core/lib/Drupal/Core/Form/FormBuilder.php
+++ b/core/lib/Drupal/Core/Form/FormBuilder.php
@@ -740,35 +740,35 @@ public function prepareForm($form_id, &$form, &$form_state) {
     if (!isset($form['#validate'])) {
       // Ensure that modules can rely on #validate being set.
       $form['#validate'] = array();
-      if (isset($form_state['build_info']['callback_object'])) {
-        $form['#validate'][] = array($form_state['build_info']['callback_object'], 'validateForm');
-      }
-      // Check for a handler specific to $form_id.
-      elseif (function_exists($form_id . '_validate')) {
-        $form['#validate'][] = $form_id . '_validate';
-      }
-      // Otherwise check whether this is a shared form and whether there is a
-      // handler for the shared $form_id.
-      elseif (isset($form_state['build_info']['base_form_id']) && function_exists($form_state['build_info']['base_form_id'] . '_validate')) {
-        $form['#validate'][] = $form_state['build_info']['base_form_id'] . '_validate';
-      }
+    }
+    if (isset($form_state['build_info']['callback_object'])) {
+      $form['#validate'][] = array($form_state['build_info']['callback_object'], 'validateForm');
+    }
+    // Check for a handler specific to $form_id.
+    elseif (function_exists($form_id . '_validate')) {
+      $form['#validate'][] = $form_id . '_validate';
+    }
+    // Otherwise check whether this is a shared form and whether there is a
+    // handler for the shared $form_id.
+    elseif (isset($form_state['build_info']['base_form_id']) && function_exists($form_state['build_info']['base_form_id'] . '_validate')) {
+      $form['#validate'][] = $form_state['build_info']['base_form_id'] . '_validate';
     }
 
     if (!isset($form['#submit'])) {
       // Ensure that modules can rely on #submit being set.
       $form['#submit'] = array();
-      if (isset($form_state['build_info']['callback_object'])) {
-        $form['#submit'][] = array($form_state['build_info']['callback_object'], 'submitForm');
-      }
-      // Check for a handler specific to $form_id.
-      elseif (function_exists($form_id . '_submit')) {
-        $form['#submit'][] = $form_id . '_submit';
-      }
-      // Otherwise check whether this is a shared form and whether there is a
-      // handler for the shared $form_id.
-      elseif (isset($form_state['build_info']['base_form_id']) && function_exists($form_state['build_info']['base_form_id'] . '_submit')) {
-        $form['#submit'][] = $form_state['build_info']['base_form_id'] . '_submit';
-      }
+    }
+    if (isset($form_state['build_info']['callback_object'])) {
+      $form['#submit'][] = array($form_state['build_info']['callback_object'], 'submitForm');
+    }
+    // Check for a handler specific to $form_id.
+    elseif (function_exists($form_id . '_submit')) {
+      $form['#submit'][] = $form_id . '_submit';
+    }
+    // Otherwise check whether this is a shared form and whether there is a
+    // handler for the shared $form_id.
+    elseif (isset($form_state['build_info']['base_form_id']) && function_exists($form_state['build_info']['base_form_id'] . '_submit')) {
+      $form['#submit'][] = $form_state['build_info']['base_form_id'] . '_submit';
     }
 
     // If no #theme has been set, automatically apply theme suggestions.
diff --git a/core/modules/system/lib/Drupal/system/Tests/Form/FormDefaultHandlersTest.php b/core/modules/system/lib/Drupal/system/Tests/Form/FormDefaultHandlersTest.php
new file mode 100644
index 0000000..481c193
--- /dev/null
+++ b/core/modules/system/lib/Drupal/system/Tests/Form/FormDefaultHandlersTest.php
@@ -0,0 +1,92 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Form\FormDefaultHandlersTest.
+ */
+
+namespace Drupal\system\Tests\Form;
+
+use Drupal\Core\Form\FormInterface;
+use Drupal\simpletest\DrupalUnitTestBase;
+
+/**
+ * Tests automatically added form handlers.
+ */
+class FormDefaultHandlersTest extends DrupalUnitTestBase implements FormInterface {
+
+  public static $modules = array('system');
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Form handlers',
+      'description' => 'Tests automatically added form handlers.',
+      'group' => 'Form API',
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'test_form_handlers';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, array &$form_state) {
+    $form['#validate'][] = array($this, 'customValidateForm');
+    $form['#submit'][] = array($this, 'customSubmitForm');
+    $form['submit'] = array('#type' => 'submit', '#value' => 'Save');
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function customValidateForm(array &$form, array &$form_state) {
+    $form_state['test_handlers']['validate'][] = __FUNCTION__;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, array &$form_state) {
+    $form_state['test_handlers']['validate'][] = __FUNCTION__;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function customSubmitForm(array &$form, array &$form_state) {
+    $form_state['test_handlers']['submit'][] = __FUNCTION__;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, array &$form_state) {
+    $form_state['test_handlers']['submit'][] = __FUNCTION__;
+  }
+
+  /**
+   * Tests that default handlers are added even if custom are specified.
+   */
+  function testLimitValidationErrors() {
+    $form_state['values'] = array();
+    $form_builder = $this->container->get('form_builder');
+    $form_builder->submitForm($this, $form_state);
+
+    $handlers = $form_state['test_handlers'];
+
+    $this->assertIdentical(count($handlers['validate']), 2);
+    $this->assertIdentical($handlers['validate'][0], 'customValidateForm');
+    $this->assertIdentical($handlers['validate'][1], 'validateForm');
+
+    $this->assertIdentical(count($handlers['submit']), 2);
+    $this->assertIdentical($handlers['submit'][0], 'customSubmitForm');
+    $this->assertIdentical($handlers['submit'][1], 'submitForm');
+  }
+
+}