diff --git a/core/includes/form.inc b/core/includes/form.inc
index 0ef70f8..4971885 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -2893,22 +2893,21 @@ function theme_details($variables) {
 }
 
 /**
- * Returns HTML for a radio button form element.
+ * Prepares an element to be rendered as a checkbox.
+ *
+ * @param array $element
+ *   An associative array containing the properties of the element.
+ *     Properties used: #required, #return_value, #value, #attributes, #title,
+ *     #description
  *
  * Note: The input "name" attribute needs to be sanitized before output, which
  *       is currently done by initializing Drupal\Core\Template\Attribute with
  *       all the attributes.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
- *     Properties used: #required, #return_value, #value, #attributes, #title,
- *     #description
- *
- * @ingroup themeable
+ * @return
+ *   The modified element with checkbox attributes.
  */
-function theme_radio($variables) {
-  $element = $variables['element'];
+function form_pre_render_radio($element) {
   $element['#attributes']['type'] = 'radio';
   element_set_attributes($element, array('id', 'name', '#return_value' => 'value'));
 
@@ -2917,7 +2916,7 @@ function theme_radio($variables) {
   }
   _form_set_attributes($element, array('form-radio'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />';
+  return $element;
 }
 
 /**
@@ -3164,19 +3163,17 @@ function form_process_radios($element) {
 }
 
 /**
- * Returns HTML for a checkbox form element.
+ * Prepares an element to be rendered as a checkbox.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #return_value, #description, #required,
  *     #attributes, #checked.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with checkbox attributes.
  */
-function theme_checkbox($variables) {
-  $element = $variables['element'];
-  $t = get_t();
+function form_pre_render_checkbox($element) {
   $element['#attributes']['type'] = 'checkbox';
   element_set_attributes($element, array('id', 'name', '#return_value' => 'value'));
 
@@ -3186,7 +3183,7 @@ function theme_checkbox($variables) {
   }
   _form_set_attributes($element, array('form-checkbox'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />';
+  return $element;
 }
 
 /**
@@ -4087,34 +4084,49 @@ function form_process_autocomplete($element, &$form_state) {
 }
 
 /**
- * Returns HTML for a submit button form element.
+ * Preprocesses variables for input form elements.
  *
- * @param $variables
+ * @param array $variables
  *   An associative array containing:
  *   - element: An associative array containing the properties of the element.
- *     Properties used: #attributes, #button_type, #name, #value.
  *
  * @ingroup themeable
  */
-function theme_submit($variables) {
-  return theme('button', $variables['element']);
+function template_preprocess_input(&$variables) {
+  $element = $variables['element'];
+  $variables['attributes'] = new Attribute($element['#attributes']);
 }
 
 /**
- * Returns HTML for a button form element.
+ * Returns HTML for an input form element.
  *
- * @param $variables
+ * @param array $variables
  *   An associative array containing:
  *   - element: An associative array containing the properties of the element.
+ *     Properties used: #attributes.
+ *
+ * @ingroup themeable
+ */
+function theme_input($variables) {
+  $element = $variables['element'];
+  $attributes = $variables['attributes'];
+  return '<input' . $attributes . ' />' . drupal_render_children($element);
+}
+
+/**
+ * Prepares an element to be rendered as a button.
+ *
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #attributes, #button_type, #name, #value.
  *
  * The #button_type property accepts any value, though core themes have css that
  * styles the following button_types appropriately: 'primary', 'danger'.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with button attributes.
  */
-function theme_button($variables) {
-  $element = $variables['element'];
+function form_pre_render_button($element) {
   $element['#attributes']['type'] = 'submit';
   element_set_attributes($element, array('id', 'name', 'value'));
 
@@ -4129,24 +4141,23 @@ function theme_button($variables) {
     $element['#attributes']['class'][] = 'form-button-disabled';
   }
 
-  return '<input' . new Attribute($element['#attributes']) . ' />';
+  return $element;
 }
 
 /**
- * Returns HTML for an image button form element.
+ * Prepares an element to be rendered as an image button.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #attributes, #button_type, #name, #value, #title, #src.
  *
  * The #button_type property accepts any value, though core themes have css that
  * styles the following button_types appropriately: 'primary', 'danger'.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with image button attributes.
  */
-function theme_image_button($variables) {
-  $element = $variables['element'];
+function form_pre_render_image_button($element) {
   $element['#attributes']['type'] = 'image';
   element_set_attributes($element, array('id', 'name', 'value'));
 
@@ -4167,64 +4178,62 @@ function theme_image_button($variables) {
     $element['#attributes']['class'][] = 'image-button-disabled';
   }
 
-  return '<input' . new Attribute($element['#attributes']) . ' />';
+  return $element;
 }
 
 /**
- * Returns HTML for a hidden form element.
+ * Prepares an element to be rendered as a hidden form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #name, #value, #attributes.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with hidden type attributes.
  */
-function theme_hidden($variables) {
-  $element = $variables['element'];
+function form_pre_render_hidden($element) {
   $element['#attributes']['type'] = 'hidden';
   element_set_attributes($element, array('name', 'value'));
-  return '<input' . new Attribute($element['#attributes']) . " />\n";
+
+  return $element;
 }
 
 /**
- * Returns HTML for a textfield form element.
+ * Prepares an element to be rendered as a textfield form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #description, #size, #maxlength,
  *     #placeholder, #required, #attributes.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with textfield attributes.
  */
-function theme_textfield($variables) {
-  $element = $variables['element'];
+function form_pre_render_textfield($element) {
   $element['#attributes']['type'] = 'text';
   element_set_attributes($element, array('id', 'name', 'value', 'size', 'maxlength', 'placeholder'));
   _form_set_attributes($element, array('form-text'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />' . drupal_render_children($element);
+  return $element;
 }
 
 /**
- * Returns HTML for an email form element.
+ * Prepares an element to be rendered as an email form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #description, #size, #maxlength,
  *     #placeholder, #required, #attributes.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with email attributes.
  */
-function theme_email($variables) {
-  $element = $variables['element'];
+function form_pre_render_email($element) {
   $element['#attributes']['type'] = 'email';
   element_set_attributes($element, array('id', 'name', 'value', 'size', 'maxlength', 'placeholder'));
   _form_set_attributes($element, array('form-email'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />' . drupal_render_children($element);
+  return $element;
 }
 
 /**
@@ -4242,69 +4251,60 @@ function form_validate_email(&$element, &$form_state) {
 }
 
 /**
- * Returns HTML for a tel form element.
+ * Prepares an element to be rendered as a tel form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #description, #size, #maxlength,
  *     #placeholder, #required, #attributes.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with tel attributes.
  */
-function theme_tel($variables) {
-  $element = $variables['element'];
+function form_pre_render_tel($element) {
   $element['#attributes']['type'] = 'tel';
   element_set_attributes($element, array('id', 'name', 'value', 'size', 'maxlength', 'placeholder'));
   _form_set_attributes($element, array('form-tel'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />' . drupal_render_children($element);
+  return $element;
 }
 
 /**
- * Returns HTML for a number form element.
+ * Prepares an element to be rendered as a number form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #description, #min, #max, #placeholder,
  *     #required, #attributes, #step.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with number attributes.
  */
-function theme_number($variables) {
-  $element = $variables['element'];
-
+function form_pre_render_number($element) {
   $element['#attributes']['type'] = 'number';
   element_set_attributes($element, array('id', 'name', 'value', 'step', 'min', 'max', 'placeholder'));
   _form_set_attributes($element, array('form-number'));
 
-  $output = '<input' . new Attribute($element['#attributes']) . ' />';
-
-  return $output;
+  return $element;
 }
 
 /**
- * Returns HTML for a range form element.
+ * Prepares an element to be rendered as a range form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #description, #min, #max, #attributes,
  *     #step.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with range attributes.
  */
-function theme_range($variables) {
-  $element = $variables['element'];
-
+function form_pre_render_range($element) {
   $element['#attributes']['type'] = 'range';
   element_set_attributes($element, array('id', 'name', 'value', 'step', 'min', 'max'));
   _form_set_attributes($element, array('form-range'));
 
-  $output = '<input' . new Attribute($element['#attributes']) . ' />';
-
-  return $output;
+  return $element;
 }
 
 /**
@@ -4378,43 +4378,41 @@ function form_type_range_value($element, $input = FALSE) {
 }
 
 /**
- * Returns HTML for a URL form element.
+ * Prepares an element to be rendered as a URL form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #description, #size, #maxlength,
  *     #placeholder, #required, #attributes.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with url attributes.
  */
-function theme_url($variables) {
-  $element = $variables['element'];
+function form_pre_render_url($element) {
   $element['#attributes']['type'] = 'url';
   element_set_attributes($element, array('id', 'name', 'value', 'size', 'maxlength', 'placeholder'));
   _form_set_attributes($element, array('form-url'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />' . drupal_render_children($element);
+  return $element;
 }
 
 /**
- * Returns HTML for a search form element.
+ * Prepares an element to be rendered as a search form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #description, #size, #maxlength,
  *     #placeholder, #required, #attributes.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with search attributes.
  */
-function theme_search($variables) {
-  $element = $variables['element'];
+function form_pre_render_search($element) {
   $element['#attributes']['type'] = 'search';
   element_set_attributes($element, array('id', 'name', 'value', 'size', 'maxlength', 'placeholder'));
   _form_set_attributes($element, array('form-search'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />' . drupal_render_children($element);
+  return $element;
 }
 
 /**
@@ -4454,22 +4452,21 @@ function form_validate_color(&$element, &$form_state) {
 }
 
 /**
- * Returns HTML for a color form element.
+ * Prepares an element to be rendered as a color form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #description, #attributes.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with color attributes.
  */
-function theme_color($variables) {
-  $element = $variables['element'];
+function form_pre_render_color($element) {
   $element['#attributes']['type'] = 'color';
   element_set_attributes($element, array('id', 'name', 'value'));
   _form_set_attributes($element, array('form-color'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />' . drupal_render_children($element);
+  return $element;
 }
 
 /**
@@ -4527,23 +4524,22 @@ function theme_textarea($variables) {
 }
 
 /**
- * Returns HTML for a password form element.
+ * Prepares an element to be rendered as a password form element.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #value, #description, #size, #maxlength,
  *     #placeholder, #required, #attributes.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with password attributes.
  */
-function theme_password($variables) {
-  $element = $variables['element'];
+function form_pre_render_password($element) {
   $element['#attributes']['type'] = 'password';
   element_set_attributes($element, array('id', 'name', 'size', 'maxlength', 'placeholder'));
   _form_set_attributes($element, array('form-text'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />';
+  return $element;
 }
 
 /**
@@ -4574,26 +4570,25 @@ function form_process_weight($element) {
 }
 
 /**
- * Returns HTML for a file upload form element.
+ * Prepares an element to be rendered as a file upload form element.
  *
  * For assistance with handling the uploaded file correctly, see the API
  * provided by file.inc.
  *
- * @param $variables
- *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
+ * @param array $element
+ *   An associative array containing the properties of the element.
  *     Properties used: #title, #name, #size, #description, #required,
  *     #attributes.
  *
- * @ingroup themeable
+ * @return
+ *   The modified element with file attributes.
  */
-function theme_file($variables) {
-  $element = $variables['element'];
+function form_pre_render_file($element) {
   $element['#attributes']['type'] = 'file';
   element_set_attributes($element, array('id', 'name', 'size'));
   _form_set_attributes($element, array('form-file'));
 
-  return '<input' . new Attribute($element['#attributes']) . ' />';
+  return $element;
 }
 
 /**
diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 35b9cd3..3c4a3d0 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -3244,6 +3244,9 @@ function drupal_common_theme() {
       'variables' => array('primary' => array(), 'secondary' => array()),
     ),
     // From form.inc.
+    'input' => array(
+      'render element' => 'element',
+    ),
     'select' => array(
       'render element' => 'element',
     ),
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 6d16229..34279d3 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -296,8 +296,9 @@ function system_element_info() {
     '#is_button' => TRUE,
     '#executes_submit_callback' => TRUE,
     '#limit_validation_errors' => FALSE,
+    '#pre_render' => array('form_pre_render_button'),
     '#process' => array('form_process_button', 'ajax_process_form'),
-    '#theme_wrappers' => array('button'),
+    '#theme_wrappers' => array('input__button'),
   );
   $types['button'] = array(
     '#input' => TRUE,
@@ -305,27 +306,30 @@ function system_element_info() {
     '#is_button' => TRUE,
     '#executes_submit_callback' => FALSE,
     '#limit_validation_errors' => FALSE,
+    '#pre_render' => array('form_pre_render_button'),
     '#process' => array('form_process_button', 'ajax_process_form'),
-    '#theme_wrappers' => array('button'),
+    '#theme_wrappers' => array('input__button'),
   );
   $types['image_button'] = array(
     '#input' => TRUE,
     '#is_button' => TRUE,
     '#executes_submit_callback' => TRUE,
     '#limit_validation_errors' => FALSE,
+    '#pre_render' => array('form_pre_render_image_button'),
     '#process' => array('form_process_button', 'ajax_process_form'),
     '#return_value' => TRUE,
     '#has_garbage_value' => TRUE,
     '#src' => NULL,
-    '#theme_wrappers' => array('image_button'),
+    '#theme_wrappers' => array('input__image_button'),
   );
   $types['textfield'] = array(
     '#input' => TRUE,
     '#size' => 60,
     '#maxlength' => 128,
     '#autocomplete_path' => FALSE,
+    '#pre_render' => array('form_pre_render_textfield'),
     '#process' => array('form_process_autocomplete', 'ajax_process_form', 'form_process_pattern'),
-    '#theme' => 'textfield',
+    '#theme' => 'input__textfield',
     '#theme_wrappers' => array('form_element'),
   );
   $types['tel'] = array(
@@ -333,8 +337,9 @@ function system_element_info() {
     '#size' => 30,
     '#maxlength' => 128,
     '#autocomplete_path' => FALSE,
+    '#pre_render' => array('form_pre_render_tel'),
     '#process' => array('form_process_autocomplete', 'ajax_process_form', 'form_process_pattern'),
-    '#theme' => 'tel',
+    '#theme' => 'input__tel',
     '#theme_wrappers' => array('form_element'),
   );
   $types['email'] = array(
@@ -343,9 +348,10 @@ function system_element_info() {
     // user.module is not loaded in case of early bootstrap errors.
     '#maxlength' => defined('EMAIL_MAX_LENGTH') ? EMAIL_MAX_LENGTH : 255,
     '#autocomplete_path' => FALSE,
+    '#pre_render' => array('form_pre_render_email'),
     '#process' => array('form_process_autocomplete', 'ajax_process_form', 'form_process_pattern'),
     '#element_validate' => array('form_validate_email'),
-    '#theme' => 'email',
+    '#theme' => 'input__email',
     '#theme_wrappers' => array('form_element'),
   );
   $types['url'] = array(
@@ -353,9 +359,10 @@ function system_element_info() {
     '#size' => 60,
     '#maxlength' => 255,
     '#autocomplete_path' => FALSE,
+    '#pre_render' => array('form_pre_render_url'),
     '#process' => array('form_process_autocomplete', 'ajax_process_form', 'form_process_pattern'),
     '#element_validate' => array('form_validate_url'),
-    '#theme' => 'url',
+    '#theme' => 'input__url',
     '#theme_wrappers' => array('form_element'),
   );
   $types['search'] = array(
@@ -363,16 +370,18 @@ function system_element_info() {
     '#size' => 60,
     '#maxlength' => 128,
     '#autocomplete_path' => FALSE,
+    '#pre_render' => array('form_pre_render_search'),
     '#process' => array('form_process_autocomplete', 'ajax_process_form'),
-    '#theme' => 'search',
+    '#theme' => 'input__search',
     '#theme_wrappers' => array('form_element'),
   );
   $types['number'] = array(
     '#input' => TRUE,
     '#step' => 1,
+    '#pre_render' => array('form_pre_render_number'),
     '#process' => array('ajax_process_form'),
     '#element_validate' => array('form_validate_number'),
-    '#theme' => 'number',
+    '#theme' => 'input__number',
     '#theme_wrappers' => array('form_element'),
   );
   $types['range'] = array(
@@ -380,16 +389,18 @@ function system_element_info() {
     '#step' => 1,
     '#min' => 0,
     '#max' => 100,
+    '#pre_render' => array('form_pre_render_range'),
     '#process' => array('ajax_process_form'),
     '#element_validate' => array('form_validate_number'),
-    '#theme' => 'range',
+    '#theme' => 'input__range',
     '#theme_wrappers' => array('form_element'),
   );
   $types['color'] = array(
     '#input' => TRUE,
+    '#pre_render' => array('form_pre_render_color'),
     '#process' => array('ajax_process_form'),
     '#element_validate' => array('form_validate_color'),
-    '#theme' => 'color',
+    '#theme' => 'input__color',
     '#theme_wrappers' => array('form_element'),
   );
   $types['machine_name'] = array(
@@ -408,8 +419,9 @@ function system_element_info() {
     '#input' => TRUE,
     '#size' => 60,
     '#maxlength' => 128,
+    '#pre_render' => array('form_pre_render_password'),
     '#process' => array('ajax_process_form', 'form_process_pattern'),
-    '#theme' => 'password',
+    '#theme' => 'input__password',
     '#theme_wrappers' => array('form_element'),
   );
   $types['password_confirm'] = array(
@@ -435,8 +447,9 @@ function system_element_info() {
   $types['radio'] = array(
     '#input' => TRUE,
     '#default_value' => NULL,
+    '#pre_render' => array('form_pre_render_radio'),
     '#process' => array('ajax_process_form'),
-    '#theme' => 'radio',
+    '#theme' => 'input__radio',
     '#theme_wrappers' => array('form_element'),
     '#title_display' => 'after',
   );
@@ -449,8 +462,9 @@ function system_element_info() {
   $types['checkbox'] = array(
     '#input' => TRUE,
     '#return_value' => 1,
-    '#theme' => 'checkbox',
+    '#pre_render' => array('form_pre_render_checkbox'),
     '#process' => array('form_process_checkbox', 'ajax_process_form'),
+    '#theme' => 'input__checkbox',
     '#theme_wrappers' => array('form_element'),
     '#title_display' => 'after',
   );
@@ -480,8 +494,9 @@ function system_element_info() {
   );
   $types['file'] = array(
     '#input' => TRUE,
+    '#pre_render' => array('form_pre_render_file'),
     '#size' => 60,
-    '#theme' => 'file',
+    '#theme' => 'input__file',
     '#theme_wrappers' => array('form_element'),
   );
   $types['tableselect'] = array(
@@ -507,8 +522,9 @@ function system_element_info() {
   );
   $types['hidden'] = array(
     '#input' => TRUE,
+    '#pre_render' => array('form_pre_render_hidden'),
     '#process' => array('ajax_process_form'),
-    '#theme' => 'hidden',
+    '#theme' => 'input__hidden',
   );
   $types['value'] = array(
     '#input' => TRUE,