With Bootstrap, how do I show radio inputs as buttons?

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet"/>    
<div class="btn-group" data-toggle="buttons">
      <label class="btn btn-primary">
        <input type="radio" name="options" id="option1"> Option 1
      </label>
      <label class="btn btn-primary">
        <input type="radio" name="options" id="option2"> Option 2
      </label>
      <label class="btn btn-primary">
        <input type="radio" name="options" id="option3"> Option 3
      </label>
</div>