diff --git a/core/includes/form.inc b/core/includes/form.inc
index ac789e1..be5324a 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -2005,6 +2005,10 @@ function _form_builder_handle_input_element($form_id, &$element, &$form_state) {
   // submitted with drupal_form_submit() may bypass access restriction and be
   // treated as high-privilege users instead.
   $process_input = empty($element['#disabled']) && ($form_state['programmed'] || ($form_state['process_input'] && (!isset($element['#access']) || $element['#access'])));
+  $loadable = isset($element['#load']) && isset($form_state['callbacks']['load'][$element['#load']]);
+  if ($loadable) {
+    $form_state['loadables'][$element['#load']][] = $element['#array_parents'];
+  }
 
   // Set the element's #value property.
   if (!isset($element['#value']) && !array_key_exists('#value', $element)) {
@@ -2046,6 +2050,10 @@ function _form_builder_handle_input_element($form_id, &$element, &$form_state) {
     }
     // Load defaults.
     if (!isset($element['#value'])) {
+      if ($loadable) {
+        $function = $form_state['callbacks']['load'][$element['#load']];
+        $element['#default_value'] = $function($element);
+      }
       // Call #type_value without a second argument to request default_value handling.
       if (function_exists($value_callback)) {
         $element['#value'] = $value_callback($element, FALSE, $form_state);
diff --git a/core/modules/aggregator/aggregator.admin.inc b/core/modules/aggregator/aggregator.admin.inc
index 718e79c..25fa8ce 100644
--- a/core/modules/aggregator/aggregator.admin.inc
+++ b/core/modules/aggregator/aggregator.admin.inc
@@ -428,14 +428,15 @@ function aggregator_admin_refresh_feed($feed) {
  * @see aggregator_admin_form_submit()
  * @ingroup forms
  */
-function aggregator_admin_form($form, $form_state) {
+function aggregator_admin_form($form, &$form_state) {
   // Global aggregator settings.
   $form['aggregator_allowed_html_tags'] = array(
     '#type' => 'textfield',
     '#title' => t('Allowed HTML tags'),
     '#size' => 80,
     '#maxlength' => 255,
-    '#default_value' => config('aggregator.settings')->get('items.allowed_html'),
+    '#load' => 'config',
+    '#config_key' => 'items.allowed_html',
     '#description' => t('A space-separated list of HTML tags allowed in the content of feed items. Disallowed tags are stripped from the content.'),
   );
 
@@ -484,7 +485,8 @@ function aggregator_admin_form($form, $form_state) {
       '#title' => t('Fetcher'),
       '#description' => t('Fetchers download data from an external source. Choose a fetcher suitable for the external source you would like to download from.'),
       '#options' => $fetchers,
-      '#default_value' => config('aggregator.settings')->get('fetcher'),
+      '#load' => 'config',
+      '#config_key' => 'fetcher',
     );
   }
   if (count($parsers) > 1) {
@@ -493,7 +495,8 @@ function aggregator_admin_form($form, $form_state) {
       '#title' => t('Parser'),
       '#description' => t('Parsers transform downloaded data into standard structures. Choose a parser suitable for the type of feeds you would like to aggregate.'),
       '#options' => $parsers,
-      '#default_value' => config('aggregator.settings')->get('parser'),
+      '#load' => 'config',
+      '#config_key' => 'parser',
     );
   }
   if (count($processors) > 1) {
@@ -502,7 +505,8 @@ function aggregator_admin_form($form, $form_state) {
       '#title' => t('Processors'),
       '#description' => t('Processors act on parsed feed data, for example they store feed items. Choose the processors suitable for your task.'),
       '#options' => $processors,
-      '#default_value' => config('aggregator.settings')->get('processors'),
+      '#load' => 'config',
+      '#config_key' => 'processors',
     );
   }
   if (count($basic_conf)) {
@@ -518,35 +522,12 @@ function aggregator_admin_form($form, $form_state) {
 
   // Implementing modules will expect an array at $form['modules'].
   $form['modules'] = array();
+  $form['#config'] = config('aggregator.settings');
 
   return system_config_form($form, $form_state);
 }
 
 /**
- * Form submission handler for aggregator_admin_form().
- */
-function aggregator_admin_form_submit($form, &$form_state) {
-  $config = config('aggregator.settings');
-  $config
-    ->set('items.allowed_html', $form_state['values']['aggregator_allowed_html_tags'])
-    ->set('items.expire', $form_state['values']['aggregator_clear'])
-    ->set('items.teaser_length', $form_state['values']['aggregator_teaser_length'])
-    ->set('source.list_max', $form_state['values']['aggregator_summary_items'])
-    ->set('source.category_selector', $form_state['values']['aggregator_category_selector']);
-
-  if (isset($form_state['values']['aggregator_fetcher'])) {
-    $config->set('fetcher', $form_state['values']['aggregator_fetcher']);
-  }
-  if (isset($form_state['values']['aggregator_parser'])) {
-    $config->set('parser', $form_state['values']['aggregator_parser']);
-  }
-  if (isset($form_state['values']['aggregator_processors'])) {
-    $config->set('processors', array_filter($form_state['values']['aggregator_processors']));
-  }
-  $config->save();
-}
-
-/**
  * Form constructor to add/edit/delete aggregator categories.
  *
  * @param $edit
diff --git a/core/modules/aggregator/aggregator.processor.inc b/core/modules/aggregator/aggregator.processor.inc
index c12c90f..4303618 100644
--- a/core/modules/aggregator/aggregator.processor.inc
+++ b/core/modules/aggregator/aggregator.processor.inc
@@ -95,7 +95,8 @@ function aggregator_form_aggregator_admin_form_alter(&$form, $form_state) {
     $form['modules']['aggregator']['aggregator_summary_items'] = array(
       '#type' => 'select',
       '#title' => t('Number of items shown in listing pages'),
-      '#default_value' => config('aggregator.settings')->get('source.list_max'),
+      '#load' => 'config',
+      '#config_key' => 'source.list_max',
       '#empty_value' => 0,
       '#options' => $items,
     );
@@ -103,7 +104,8 @@ function aggregator_form_aggregator_admin_form_alter(&$form, $form_state) {
     $form['modules']['aggregator']['aggregator_clear'] = array(
       '#type' => 'select',
       '#title' => t('Discard items older than'),
-      '#default_value' => config('aggregator.settings')->get('items.expire'),
+      '#load' => 'config',
+      '#config_key' => 'items.expire',
       '#options' => $period,
       '#description' => t('Requires a correctly configured <a href="@cron">cron maintenance task</a>.', array('@cron' => url('admin/reports/status'))),
     );
@@ -111,7 +113,8 @@ function aggregator_form_aggregator_admin_form_alter(&$form, $form_state) {
     $form['modules']['aggregator']['aggregator_category_selector'] = array(
       '#type' => 'radios',
       '#title' => t('Select categories using'),
-      '#default_value' => config('aggregator.settings')->get('source.category_selector'),
+      '#load' => 'config',
+      '#config_key' => 'source.category_selector',
       '#options' => array('checkboxes' => t('checkboxes'),
       'select' => t('multiple selector')),
       '#description' => t('For a small number of categories, checkboxes are easier to use, while a multiple selector works well with large numbers of categories.'),
@@ -119,7 +122,8 @@ function aggregator_form_aggregator_admin_form_alter(&$form, $form_state) {
     $form['modules']['aggregator']['aggregator_teaser_length'] = array(
       '#type' => 'select',
       '#title' => t('Length of trimmed description'),
-      '#default_value' => config('aggregator.settings')->get('items.teaser_length'),
+      '#load' => 'config',
+      '#config_key' => 'items.teaser_length',
       '#options' => drupal_map_assoc(array(0, 200, 400, 600, 800, 1000, 1200, 1400, 1600, 1800, 2000), '_aggregator_characters'),
       '#description' => t("The maximum number of characters used in the trimmed version of content.")
     );
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorConfigurationTest.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorConfigurationTest.php
index 65eb6ab..9273c3a 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorConfigurationTest.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorConfigurationTest.php
@@ -34,7 +34,7 @@ class AggregatorConfigurationTest extends AggregatorTestBase {
     $this->assertText(t('The configuration options have been saved.'));
 
     foreach ($edit as $name => $value) {
-      $this->assertFieldByName($name, $value, t('"@name" has correct default value.', array('@name' => $name)));
+      $this->assertFieldByName($name, $value);
     }
   }
 }
diff --git a/core/modules/book/book.admin.inc b/core/modules/book/book.admin.inc
index 5c414e0..dd6a086 100644
--- a/core/modules/book/book.admin.inc
+++ b/core/modules/book/book.admin.inc
@@ -35,11 +35,12 @@ function book_admin_overview() {
  */
 function book_admin_settings($form, &$form_state) {
   $types = node_type_get_names();
-  $config = config('book.settings');
+  $form['#config'] = config('book.settings');
   $form['book_allowed_types'] = array(
     '#type' => 'checkboxes',
     '#title' => t('Content types allowed in book outlines'),
-    '#default_value' => $config->get('allowed_types'),
+    '#load' => 'config',
+    '#config_key' => 'allowed_types',
     '#options' => $types,
     '#description' => t('Users with the %outline-perm permission can add all content types.', array('%outline-perm' => t('Administer book outlines'))),
     '#required' => TRUE,
@@ -47,7 +48,8 @@ function book_admin_settings($form, &$form_state) {
   $form['book_child_type'] = array(
     '#type' => 'radios',
     '#title' => t('Content type for child pages'),
-    '#default_value' => $config->get('child_type'),
+    '#load' => 'config',
+    '#config_key' => 'child_type',
     '#options' => $types,
     '#required' => TRUE,
   );
@@ -68,18 +70,6 @@ function book_admin_settings_validate($form, &$form_state) {
 }
 
 /**
- * Form submission handler for book_admin_settings().
- *
- * @see book_admin_settings_validate()
- */
-function book_admin_settings_submit($form, &$form_state) {
-  config('book.settings')
-    ->set('allowed_types', $form_state['values']['book_allowed_types'])
-    ->set('child_type', $form_state['values']['book_child_type'])
-    ->save();
- }
-
-/**
  * Form constructor for administering a single book's hierarchy.
  *
  * @param Drupal\node\Node $node
diff --git a/core/modules/book/book.module b/core/modules/book/book.module
index 7e7ca52..26713bd 100644
--- a/core/modules/book/book.module
+++ b/core/modules/book/book.module
@@ -342,22 +342,15 @@ function book_block_configure($delta = '') {
     '#type' => 'radios',
     '#title' => t('Book navigation block display'),
     '#options' => $options,
-    '#default_value' => config('book.settings')->get('block.navigation.mode'),
+    '#load' => 'config',
+    '#config' => config('book.settings'),
+    '#config_key' => 'block.navigation.mode',
     '#description' => t("If <em>Show block on all pages</em> is selected, the block will contain the automatically generated menus for all of the site's books. If <em>Show block only on book pages</em> is selected, the block will contain only the one menu corresponding to the current page's book. In this case, if the current page is not in a book, no block will be displayed. The <em>Page specific visibility settings</em> or other visibility settings can be used in addition to selectively display this block."),
-    );
-
+  );
   return $form;
 }
 
 /**
- * Implements hook_block_save().
- */
-function book_block_save($delta = '', $edit = array()) {
-  $block = array();
-  config('book.settings')->set('block.navigation.mode', $edit['book_block_mode'])->save();
-}
-
-/**
  * Returns HTML for a link to a book title when used as a block title.
  *
  * @param $variables
diff --git a/core/modules/contact/contact.module b/core/modules/contact/contact.module
index 1ba70b9..c749cb6 100644
--- a/core/modules/contact/contact.module
+++ b/core/modules/contact/contact.module
@@ -254,7 +254,8 @@ function contact_form_user_admin_settings_alter(&$form, &$form_state) {
     '#type' => 'checkbox',
     '#title' => t('Enable the personal contact form by default for new users.'),
     '#description' => t('Changing this setting will not affect existing users.'),
-    '#default_value' => config('contact.settings')->get('user_default_enabled'),
+    '#load' => 'config',
+    '#config_key' => 'user_default_enabled',
   );
   // Add submit handler to save contact configuration.
   $form['#submit'][] = 'contact_form_user_admin_settings_submit';
diff --git a/core/modules/dblog/dblog.module b/core/modules/dblog/dblog.module
index 2e8422f..2d98c95 100644
--- a/core/modules/dblog/dblog.module
+++ b/core/modules/dblog/dblog.module
@@ -169,7 +169,8 @@ function dblog_form_system_logging_settings_alter(&$form, $form_state) {
   $form['dblog_row_limit'] = array(
     '#type' => 'select',
     '#title' => t('Database log messages to keep'),
-    '#default_value' => config('dblog.settings')->get('row_limit'),
+    '#load' => 'config',
+    '#config_key' => 'row_limit',
     '#options' => array(0 => t('All')) + drupal_map_assoc(array(100, 1000, 10000, 100000, 1000000)),
     '#description' => t('The maximum number of messages to keep in the database log. Requires a <a href="@cron">cron maintenance task</a>.', array('@cron' => url('admin/reports/status')))
   );
diff --git a/core/modules/forum/forum.admin.inc b/core/modules/forum/forum.admin.inc
index e3c564a..739b1aa 100644
--- a/core/modules/forum/forum.admin.inc
+++ b/core/modules/forum/forum.admin.inc
@@ -241,21 +241,24 @@ function forum_admin_settings($form, &$form_state) {
   $number = drupal_map_assoc(array(5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 80, 100, 150, 200, 250, 300, 350, 400, 500));
   $form['forum_hot_topic'] = array('#type' => 'select',
     '#title' => t('Hot topic threshold'),
-    '#default_value' => $config->get('topics.hot_threshold'),
+    '#load' => 'config',
+    '#config_key' => 'topics.hot_threshold',
     '#options' => $number,
     '#description' => t('The number of replies a topic must have to be considered "hot".'),
   );
   $number = drupal_map_assoc(array(10, 25, 50, 75, 100));
   $form['forum_per_page'] = array('#type' => 'select',
     '#title' => t('Topics per page'),
-    '#default_value' => $config->get('topics.page_limit'),
+    '#load' => 'config',
+    '#config_key' => 'topics.page_limit',
     '#options' => $number,
     '#description' => t('Default number of forum topics displayed per page.'),
   );
   $forder = array(1 => t('Date - newest first'), 2 => t('Date - oldest first'), 3 => t('Posts - most active first'), 4 => t('Posts - least active first'));
   $form['forum_order'] = array('#type' => 'radios',
     '#title' => t('Default order'),
-    '#default_value' => $config->get('topics.order'),
+    '#load' => 'config',
+    '#config_key' => 'topics.order',
     '#options' => $forder,
     '#description' => t('Default display order for topics.'),
   );
diff --git a/core/modules/forum/forum.module b/core/modules/forum/forum.module
index 30b1e6b..fff6123 100644
--- a/core/modules/forum/forum.module
+++ b/core/modules/forum/forum.module
@@ -663,7 +663,8 @@ function forum_block_configure($delta = '') {
   $form['block_num_' . $delta] = array(
     '#type' => 'select',
     '#title' => t('Number of topics'),
-    '#default_value' => config('forum.settings')->get('block.num_' . $delta),
+    '#load' => 'config',
+    '#config_key' => 'block.num_' . $delta,
     '#options' => drupal_map_assoc(range(2, 20)),
   );
   return $form;
diff --git a/core/modules/menu/menu.admin.inc b/core/modules/menu/menu.admin.inc
index fc38caa..81f3fda 100644
--- a/core/modules/menu/menu.admin.inc
+++ b/core/modules/menu/menu.admin.inc
@@ -712,7 +712,8 @@ function menu_configure($form, &$form_state) {
   $form['menu_secondary_links_source'] = array(
     '#type' => 'select',
     '#title' => t('Source for the Secondary links'),
-    '#default_value' => $config->get('secondary_links'),
+    '#load' => 'config',
+    '#config_key' => 'secondary_links',
     '#empty_option' => t('No Secondary links'),
     '#options' => $menu_options,
     '#tree' => FALSE,
diff --git a/core/modules/search/search.admin.inc b/core/modules/search/search.admin.inc
index 9168510..034902b 100644
--- a/core/modules/search/search.admin.inc
+++ b/core/modules/search/search.admin.inc
@@ -75,7 +75,8 @@ function search_admin_settings($form, &$form_state) {
   $form['indexing_throttle']['cron_limit'] = array(
     '#type' => 'select',
     '#title' => t('Number of items to index per cron run'),
-    '#default_value' => $config->get('index.cron_limit'),
+    '#load' => 'config',
+    '#config_key' => 'index.cron_limit',
     '#options' => $items,
     '#description' => t('The maximum number of items indexed in each pass of a <a href="@cron">cron maintenance task</a>. If necessary, reduce the number of items to prevent timeouts and memory errors while indexing.', array('@cron' => url('admin/reports/status')))
   );
@@ -90,7 +91,8 @@ function search_admin_settings($form, &$form_state) {
   $form['indexing_settings']['minimum_word_size'] = array(
     '#type' => 'number',
     '#title' => t('Minimum word length to index'),
-    '#default_value' => $config->get('index.minimum_word_size'),
+    '#load' => 'config',
+    '#config_key' => 'index.minimum_word_size',
     '#min' => 1,
     '#max' => 1000,
     '#description' => t('The number of characters a word has to be to be indexed. A lower setting means better search result ranking, but also a larger database. Each search query must contain at least one keyword that is this size (or longer).')
@@ -98,7 +100,8 @@ function search_admin_settings($form, &$form_state) {
   $form['indexing_settings']['overlap_cjk'] = array(
     '#type' => 'checkbox',
     '#title' => t('Simple CJK handling'),
-    '#default_value' => $config->get('index.overlap_cjk'),
+    '#load' => 'config',
+    '#config_key' => 'index.overlap_cjk',
     '#description' => t('Whether to apply a simple Chinese/Japanese/Korean tokenizer based on overlapping sequences. Turn this off if you want to use an external preprocessor for this instead. Does not affect other languages.')
   );
 
@@ -111,14 +114,16 @@ function search_admin_settings($form, &$form_state) {
     '#type' => 'checkboxes',
     '#title' => t('Active modules'),
     '#title_display' => 'invisible',
-    '#default_value' => $config->get('active_modules'),
+    '#load' => 'config',
+    '#config_key' => 'active_modules',
     '#options' => $module_options,
     '#description' => t('Choose which search modules are active from the available modules.')
   );
   $form['active']['default_module'] = array(
     '#title' => t('Default search module'),
     '#type' => 'radios',
-    '#default_value' => $config->get('default_module'),
+    '#load' => 'config',
+    '#config_key' => 'default_module',
     '#options' => $module_options,
     '#description' => t('Choose which search module is the default.')
   );
diff --git a/core/modules/statistics/statistics.admin.inc b/core/modules/statistics/statistics.admin.inc
index 176e2af..2d02cbc 100644
--- a/core/modules/statistics/statistics.admin.inc
+++ b/core/modules/statistics/statistics.admin.inc
@@ -294,13 +294,15 @@ function statistics_settings_form($form, &$form_state) {
   $form['access']['statistics_enable_access_log'] = array(
     '#type' => 'checkbox',
     '#title' => t('Enable access log'),
-    '#default_value' => $config->get('access_log.enabled'),
+    '#load' => 'config',
+    '#config_key' => 'access_log.enabled',
     '#description' => t('Log each page access. Required for referrer statistics.'),
   );
   $form['access']['statistics_flush_accesslog_timer'] = array(
     '#type' => 'select',
     '#title' => t('Discard access logs older than'),
-    '#default_value' => $config->get('access_log.max_lifetime'),
+    '#load' => 'config',
+    '#config_key' => 'access_log.max_lifetime',
     '#options' => array(0 => t('Never')) + drupal_map_assoc(array(3600, 10800, 21600, 32400, 43200, 86400, 172800, 259200, 604800, 1209600, 2419200, 4838400, 9676800), 'format_interval'),
     '#description' => t('Older access log entries (including referrer statistics) will be automatically discarded. (Requires a correctly configured <a href="@cron">cron maintenance task</a>.)', array('@cron' => url('admin/reports/status'))),
   );
@@ -313,7 +315,8 @@ function statistics_settings_form($form, &$form_state) {
   $form['content']['statistics_count_content_views'] = array(
     '#type' => 'checkbox',
     '#title' => t('Count content views'),
-    '#default_value' => $config->get('count_content_views'),
+    '#load' => 'config',
+    '#config_key' => 'count_content_views',
     '#description' => t('Increment a counter each time content is viewed.'),
   );
 
diff --git a/core/modules/statistics/statistics.module b/core/modules/statistics/statistics.module
index c07a1c8..1d9b580 100644
--- a/core/modules/statistics/statistics.module
+++ b/core/modules/statistics/statistics.module
@@ -325,9 +325,33 @@ function statistics_block_configure($delta = '') {
   $config = config('statistics.settings');
   // Popular content block settings
   $numbers = array('0' => t('Disabled')) + drupal_map_assoc(array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40));
-  $form['statistics_block_popular_top_day_limit'] = array('#type' => 'select', '#title' => t("Number of day's top views to display"), '#default_value' => $config->get('block.popular.top_day_limit'), '#options' => $numbers, '#description' => t('How many content items to display in "day" list.'));
-  $form['statistics_block_popular_top_all_limit'] = array('#type' => 'select', '#title' => t('Number of all time views to display'), '#default_value' => $config->get('block.popular.top_all_limit'), '#options' => $numbers, '#description' => t('How many content items to display in "all time" list.'));
-  $form['statistics_block_popular_top_recent_limit'] = array('#type' => 'select', '#title' => t('Number of most recent views to display'), '#default_value' => $config->get('block.popular.top_recent_limit'), '#options' => $numbers, '#description' => t('How many content items to display in "recently viewed" list.'));
+  $form['statistics_block_popular_top_day_limit'] = array(
+    '#type' => 'select',
+    '#title' => t("Number of day's top views to display"),
+    '#load' => 'config',
+    '#config' => $config,
+    '#config_key' => 'block.popular.top_day_limit',
+    '#options' => $numbers,
+    '#description' => t('How many content items to display in "day" list.'),
+  );
+  $form['statistics_block_popular_top_all_limit'] = array(
+    '#type' => 'select',
+    '#title' => t('Number of all time views to display'),
+    '#load' => 'config',
+    '#config' => $config,
+    '#config_key' => 'block.popular.top_all_limit',
+    '#options' => $numbers,
+    '#description' => t('How many content items to display in "all time" list.'),
+  );
+  $form['statistics_block_popular_top_recent_limit'] = array(
+    '#type' => 'select',
+    '#title' => t('Number of most recent views to display'),
+    '#load' => 'config',
+    '#config' => $config,
+    '#config_key' => 'block.popular.top_recent_limit',
+    '#options' => $numbers,
+    '#description' => t('How many content items to display in "recently viewed" list.'),
+  );
   return $form;
 }
 
diff --git a/core/modules/syslog/syslog.module b/core/modules/syslog/syslog.module
index e138656..b137640 100644
--- a/core/modules/syslog/syslog.module
+++ b/core/modules/syslog/syslog.module
@@ -50,14 +50,16 @@ function syslog_form_system_logging_settings_alter(&$form, &$form_state) {
   $form['syslog_identity'] = array(
     '#type'          => 'textfield',
     '#title'         => t('Syslog identity'),
-    '#default_value' => $config->get('identity'),
+    '#load' => 'config',
+    '#config_key' => 'identity',
     '#description'   => t('A string that will be prepended to every message logged to Syslog. If you have multiple sites logging to the same Syslog log file, a unique identity per site makes it easy to tell the log entries apart.') . $help,
   );
   if (defined('LOG_LOCAL0')) {
     $form['syslog_facility'] = array(
       '#type'          => 'select',
       '#title'         => t('Syslog facility'),
-      '#default_value' => $config->get('facility'),
+      '#load' => 'config',
+      '#config_key' => 'facility',
       '#options'       => syslog_facility_list(),
       '#description'   => t('Depending on the system configuration, Syslog and other logging tools use this code to identify or filter messages from within the entire system log.') . $help,
      );
@@ -65,7 +67,8 @@ function syslog_form_system_logging_settings_alter(&$form, &$form_state) {
   $form['syslog_format'] = array(
     '#type'          => 'textarea',
     '#title'         => t('Syslog format'),
-    '#default_value' => $config->get('format'),
+    '#load' => 'config',
+    '#config_key' => 'format',
     '#description'   => t('Specify the format of the syslog entry. Available variables are: <dl><dt><code>!base_url</code></dt><dd>Base URL of the site.</dd><dt><code>!timestamp</code></dt><dd>Unix timestamp of the log entry.</dd><dt><code>!type</code></dt><dd>The category to which this message belongs.</dd><dt><code>!ip</code></dt><dd>IP address of the user triggering the message.</dd><dt><code>!request_uri</code></dt><dd>The requested URI.</dd><dt><code>!referer</code></dt><dd>HTTP Referer if available.</dd><dt><code>!uid</code></dt><dd>User ID.</dd><dt><code>!link</code></dt><dd>A link to associate with the message.</dd><dt><code>!message</code></dt><dd>The message to store in the log.</dd></dl>'),
   );
 
diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index 3ccb13b..cc2d389 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -1479,7 +1479,7 @@ function system_ip_blocking_delete_submit($form, &$form_state) {
  * @see system_settings_form()
  */
 function system_site_information_settings($form, &$form_state) {
-  $site_config = config('system.site');
+  $form['#config'] = config('system.site');
   $site_mail = $site_config->get('mail');
   if (empty($site_mail)) {
     $site_mail = ini_get('sendmail_from');
@@ -1492,13 +1492,15 @@ function system_site_information_settings($form, &$form_state) {
   $form['site_information']['site_name'] = array(
     '#type' => 'textfield',
     '#title' => t('Site name'),
-    '#default_value' => $site_config->get('name'),
+    '#load' => 'config',
+    '#config_key' => 'name',
     '#required' => TRUE
   );
   $form['site_information']['site_slogan'] = array(
     '#type' => 'textfield',
     '#title' => t('Slogan'),
-    '#default_value' => $site_config->get('slogan'),
+    '#load' => 'config',
+    '#config_key' => 'slogan',
     '#description' => t("How this is used depends on your site's theme."),
   );
   $form['site_information']['site_mail'] = array(
@@ -1515,7 +1517,8 @@ function system_site_information_settings($form, &$form_state) {
   $form['front_page']['site_frontpage'] = array(
     '#type' => 'textfield',
     '#title' => t('Default front page'),
-    '#default_value' => ($site_config->get('page.front') != 'user' ? drupal_get_path_alias($site_config->get('page.front')) : ''),
+    '#load' => 'config',
+    '#config_key' => 'page.front' != 'user' ? drupal_get_path_alias($site_config->get('page.front')) : '',
     '#size' => 40,
     '#description' => t('Optionally, specify a relative URL to display as the front page.  Leave blank to display the default content feed.'),
     '#field_prefix' => url(NULL, array('absolute' => TRUE)),
@@ -1527,7 +1530,8 @@ function system_site_information_settings($form, &$form_state) {
   $form['error_page']['site_403'] = array(
     '#type' => 'textfield',
     '#title' => t('Default 403 (access denied) page'),
-    '#default_value' => $site_config->get('page.403'),
+    '#load' => 'config',
+    '#config_key' => 'page.403',
     '#size' => 40,
     '#description' => t('This page is displayed when the requested document is denied to the current user. Leave blank to display a generic "access denied" page.'),
     '#field_prefix' => url(NULL, array('absolute' => TRUE)),
@@ -1535,7 +1539,8 @@ function system_site_information_settings($form, &$form_state) {
   $form['error_page']['site_404'] = array(
     '#type' => 'textfield',
     '#title' => t('Default 404 (not found) page'),
-    '#default_value' => $site_config->get('page.404'),
+    '#load' => 'config',
+    '#config_key' => 'page.404',
     '#size' => 40,
     '#description' => t('This page is displayed when no other content matches the requested document. Leave blank to display a generic "page not found" page.'),
     '#field_prefix' => url(NULL, array('absolute' => TRUE)),
@@ -1581,20 +1586,6 @@ function system_site_information_settings_validate($form, &$form_state) {
 }
 
 /**
- * Form submission handler for system_site_information_settings().
- */
-function system_site_information_settings_submit($form, &$form_state) {
-  config('system.site')
-    ->set('name', $form_state['values']['site_name'])
-    ->set('mail', $form_state['values']['site_mail'])
-    ->set('slogan', $form_state['values']['site_slogan'])
-    ->set('page.front', $form_state['values']['site_frontpage'])
-    ->set('page.403', $form_state['values']['site_403'])
-    ->set('page.404', $form_state['values']['site_404'])
-    ->save();
-}
-
-/**
  * Form builder; Cron form.
  *
  * @ingroup forms
@@ -1620,25 +1611,16 @@ function system_cron_settings($form, &$form_state) {
   $form['cron']['cron_safe_threshold'] = array(
     '#type' => 'select',
     '#title' => t('Run cron every'),
-    '#default_value' => config('system.cron')->get('threshold.autorun'),
+    '#load' => 'config',
+    '#config_key' => 'threshold.autorun',
     '#options' => array(0 => t('Never')) + drupal_map_assoc(array(3600, 10800, 21600, 43200, 86400, 604800), 'format_interval'),
   );
+  $form['#config'] = config('system.cron');
 
   return system_config_form($form, $form_state);
 }
 
 /**
- * Form builder submit handler; Handle submission for cron settings.
- *
- * @ingroup forms
- */
-function system_cron_settings_submit($form, &$form_state) {
-  config('system.cron')
-    ->set('threshold.autorun', $form_state['values']['cron_safe_threshold'])
-    ->save();
-}
-
-/**
  * Submit callback; run cron.
  *
  * @ingroup forms
@@ -1665,7 +1647,8 @@ function system_logging_settings($form, &$form_state) {
   $form['error_level'] = array(
     '#type' => 'radios',
     '#title' => t('Error messages to display'),
-    '#default_value' => config('system.logging')->get('error_level'),
+    '#load' => 'config',
+    '#config_key' => 'error_level',
     '#options' => array(
       ERROR_REPORTING_HIDE => t('None'),
       ERROR_REPORTING_DISPLAY_SOME => t('Errors and warnings'),
@@ -1674,22 +1657,12 @@ function system_logging_settings($form, &$form_state) {
     ),
     '#description' => t('It is recommended that sites running on production environments do not display any errors.'),
   );
+  $form['#config'] = config('system.logging');
 
   return system_config_form($form, $form_state);
 }
 
 /**
- * Form submission handler for system_logging_settings().
- *
- * @ingroup forms
- */
-function system_logging_settings_submit($form, &$form_state) {
-  config('system.logging')
-    ->set('error_level', $form_state['values']['error_level'])
-    ->save();
-}
-
-/**
  * Form builder; Configure site performance settings.
  *
  * @ingroup forms
@@ -1697,7 +1670,7 @@ function system_logging_settings_submit($form, &$form_state) {
  */
 function system_performance_settings($form, &$form_state) {
   drupal_add_library('system', 'drupal.system');
-  $config = config('system.performance');
+  $form['#config'] = config('system.performance');
 
   $form['clear_cache'] = array(
     '#type' => 'fieldset',
@@ -1718,7 +1691,8 @@ function system_performance_settings($form, &$form_state) {
   $form['caching']['cache'] = array(
     '#type' => 'checkbox',
     '#title' => t('Cache pages for anonymous users'),
-    '#default_value' => $config->get('cache.page.enabled'),
+    '#load' => 'config',
+    '#config_key' => 'cache.page.enabled',
     '#weight' => -2,
   );
 
@@ -1727,7 +1701,8 @@ function system_performance_settings($form, &$form_state) {
   $form['caching']['page_cache_maximum_age'] = array(
     '#type' => 'select',
     '#title' => t('Expiration of cached pages'),
-    '#default_value' => $config->get('cache.page.max_age'),
+    '#load' => 'config',
+    '#config_key' => 'cache.page.max_age',
     '#options' => $period,
     '#description' => t('The maximum time an external cache can use an old version of a page.'),
   );
@@ -1746,24 +1721,27 @@ function system_performance_settings($form, &$form_state) {
     '#description' => t('External resources can be optimized automatically, which can reduce both the size and number of requests made to your website.') . $disabled_message,
   );
 
-  $js_hide = $config->get('cache.page.enabled') ? '' : ' class="js-hide"';
+  $js_hide = $form['#config']->get('cache.page.enabled') ? '' : ' class="js-hide"';
   $form['bandwidth_optimization']['page_compression'] = array(
     '#type' => 'checkbox',
     '#title' => t('Compress cached pages.'),
-    '#default_value' => $config->get('response.gzip'),
+    '#load' => 'config',
+    '#config_key' => 'response.gzip',
     '#prefix' => '<div id="page-compression-wrapper"' . $js_hide . '>',
     '#suffix' => '</div>',
   );
   $form['bandwidth_optimization']['preprocess_css'] = array(
     '#type' => 'checkbox',
     '#title' => t('Aggregate and compress CSS files.'),
-    '#default_value' => $config->get('preprocess.css'),
+    '#load' => 'config',
+    '#config_key' => 'preprocess.css',
     '#disabled' => $disabled,
   );
   $form['bandwidth_optimization']['preprocess_js'] = array(
     '#type' => 'checkbox',
     '#title' => t('Aggregate JavaScript files.'),
-    '#default_value' => $config->get('preprocess.js'),
+    '#load' => 'config',
+    '#config_key' => 'preprocess.js',
     '#disabled' => $disabled,
   );
 
@@ -1772,27 +1750,11 @@ function system_performance_settings($form, &$form_state) {
   // This form allows page compression settings to be changed, which can
   // invalidate the page cache, so it needs to be cleared on form submit.
   $form['#submit'][] = 'system_clear_page_cache_submit';
-  $form['#submit'][] = 'system_performance_settings_submit';
 
   return system_config_form($form, $form_state);
 }
 
 /**
- * Form submission handler for system_performance_settings().
- *
- * @ingroup forms
- */
-function system_performance_settings_submit($form, &$form_state) {
-  $config = config('system.performance');
-  $config->set('cache.page.enabled', $form_state['values']['cache']);
-  $config->set('cache.page.max_age', $form_state['values']['page_cache_maximum_age']);
-  $config->set('response.gzip', $form_state['values']['page_compression']);
-  $config->set('preprocess.css', $form_state['values']['preprocess_css']);
-  $config->set('preprocess.js', $form_state['values']['preprocess_js']);
-  $config->save();
-}
-
-/**
  * Submit callback; clear system caches.
  *
  * @ingroup forms
@@ -1912,20 +1874,26 @@ function system_rss_feeds_settings($form, &$form_state) {
   $form['feed_description'] = array(
     '#type' => 'textarea',
     '#title' => t('Feed description'),
-    '#default_value' => $rss_config->get('channel.description'),
+    '#load' => 'config',
+    '#config' =>  $rss_config,
+    '#config_key' => 'channel.description',
     '#description' => t('Description of your site, included in each feed.')
   );
   $form['feed_default_items'] = array(
     '#type' => 'select',
     '#title' => t('Number of items in each feed'),
-    '#default_value' => $rss_config->get('items.limit'),
+    '#load' => 'config',
+    '#config' =>  $rss_config,
+    '#config_key' => 'items.limit',
     '#options' => drupal_map_assoc(array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30)),
     '#description' => t('Default number of items to include in each feed.')
   );
   $form['feed_item_length'] = array(
     '#type' => 'select',
     '#title' => t('Feed content'),
-    '#default_value' => $rss_config->get('items.view_mode'),
+    '#load' => 'config',
+    '#config' =>  $rss_config,
+    '#config_key' => 'items.view_mode',
     '#options' => array(
       'title' => t('Titles only'),
       'teaser' => t('Titles plus teaser'),
@@ -2253,13 +2221,15 @@ function system_site_maintenance_mode($form, &$form_state) {
   $form['maintenance_mode'] = array(
     '#type' => 'checkbox',
     '#title' => t('Put site into maintenance mode'),
-    '#default_value' => $config->get('enabled'),
+    '#load' => 'config',
+    '#config_key' => 'enabled',
     '#description' => t('Visitors will only see the maintenance mode message. Only users with the "Access site in maintenance mode" <a href="@permissions-url">permission</a> will be able to access the site. Authorized users can log in directly via the <a href="@user-login">user login</a> page.', array('@permissions-url' => url('admin/config/people/permissions'), '@user-login' => url('user'))),
   );
   $form['maintenance_mode_message'] = array(
     '#type' => 'textarea',
     '#title' => t('Message to display when in maintenance mode'),
-    '#default_value' => $config->get('message'),
+    '#load' => 'config',
+    '#config_key' => 'message',
   );
 
   return system_config_form($form, $form_state);
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index c151ef0..e5d4f50 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -6,6 +6,7 @@
  */
 
 use Drupal\Core\Utility\ModuleInfo;
+use Drupal\Component\Utility\NestedArray;
 
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\Response;
@@ -3190,6 +3191,13 @@ function system_settings_form($form) {
   if (!isset($form['#theme'])) {
     $form['#theme'] = 'system_settings_form';
   }
+  $config = isset($form['#config']) ? $form['#config'] : NULL;
+  $form_state['callbacks']['load']['config'] = function ($element) use ($config) {
+    if (isset($element['#config'])) {
+      $config = $element['#config'];
+    }
+    return $config->get($element['#config_key']);
+  };
   return $form;
 }
 
@@ -3267,6 +3275,13 @@ function system_config_form($form, &$form_state) {
  * @see system_config_form()
  */
 function system_config_form_submit($form, &$form_state) {
+  foreach ($form_state['loadables']['config'] as $array_parents) {
+    $element = NestedArray::getValue($form, $array_parents);
+    $value = ($element['#type'] == 'checkboxes') ? array_keys(array_filter($element['#value'])) : $element['#value'];
+    $config = isset($element['#config']) ? $element['#config'] : $form['#config'];
+    $config->set($element['#config_key'], $value);
+  }
+  $config->save();
   drupal_set_message(t('The configuration options have been saved.'));
 }
 
diff --git a/core/modules/update/update.settings.inc b/core/modules/update/update.settings.inc
index 0a5e337..962f367 100644
--- a/core/modules/update/update.settings.inc
+++ b/core/modules/update/update.settings.inc
@@ -13,11 +13,12 @@
  * @ingroup forms
  */
 function update_settings($form, &$form_state) {
-  $config = config('update.settings');
+  $form['#config'] = config('update.settings');
   $form['update_check_frequency'] = array(
     '#type' => 'radios',
     '#title' => t('Check for updates'),
-    '#default_value' => $config->get('check.interval_days'),
+    '#load' => 'config',
+    '#config_key' => 'check.interval_days',
     '#options' => array(
       '1' => t('Daily'),
       '7' => t('Weekly'),
@@ -28,7 +29,8 @@ function update_settings($form, &$form_state) {
   $form['update_check_disabled'] = array(
     '#type' => 'checkbox',
     '#title' => t('Check for updates of disabled modules and themes'),
-    '#default_value' => $config->get('check.disabled_extensions'),
+    '#load' => 'config',
+    '#config_key' => 'check.disabled_extensions',
   );
 
   $notification_emails = $config->get('notification.emails');
@@ -43,7 +45,8 @@ function update_settings($form, &$form_state) {
   $form['update_notification_threshold'] = array(
     '#type' => 'radios',
     '#title' => t('E-mail notification threshold'),
-    '#default_value' => $config->get('notification.threshold'),
+    '#load' => 'config',
+    '#config_key' => 'notification.threshold',
     '#options' => array(
       'all' => t('All newer versions'),
       'security' => t('Only security updates'),
@@ -108,11 +111,4 @@ function update_settings_submit($form, $form_state) {
   if ($form_state['values']['update_check_disabled'] != $config->get('check.disabled_extensions')) {
     _update_cache_clear();
   }
-
-  $config
-    ->set('check.disabled_extensions', $form_state['values']['update_check_disabled'])
-    ->set('check.interval_days', $form_state['values']['update_check_frequency'])
-    ->set('notification.emails', $form_state['notify_emails'])
-    ->set('notification.threshold', $form_state['values']['update_notification_threshold'])
-    ->save();
 }