Add custom class to form fields

Having such form

<%= form_tag 'search', method: 'get', class: 'form-horizontal' do %>
     <%= label_tag  :search, 'Enter url here' %>
     <%= text_field_tag :search  %>
     <%= submit_tag 'Get it!' %>
    <% end %>

Code above adds class='form-horizontal' for form tag.

How can I add class='form-control' for each input field ?