Input preprocess

/**
* Implements template_preprocess_input().
*/
function EXAMPLE_preprocess_input(&$variables) {
  if (isset($variables['attributes']['id'])) {
    if ($variables['attributes']['id'] == 'edit-payment-information-billing-information-field-fio-0-value') {
      $variables['attributes']['placeholder'] = 'Custom placeholder';
    }
  }
}