Set label as placeholder

gistfile1.aw

<?php
hook_form_FORM_ID_alter(&$form, &$form_state, $form_id) {
  set_label_as_placeholder($form);
}

function set_label_as_placeholder(&$form) {
  foreach (element_children($form) as $name) {
    element_children($form[$name]);

    if ($form[$name]['#type'] == 'textfield') {
      $form[$name]['#attributes']['placeholde'] = $form[$name]['#title'];
      $form[$name]['#title'] = '';
    }
  }
}