Bootstrap 3 - input-group
HTML
<link rel="stylesheet" href="http://getbootstrap.com/dist/css/bootstrap.css">
<script src="http://getbootstrap.com/dist/js/bootstrap.js"></script>
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/font-awesome/4.1.0/css/font-awesome.min.css">
<div class="row">
<div class="col-xs-6">
<div class="input-group">
<input type="text" class="form-control"/>
<span class="input-group-addon">
<i class="fa fa-search"></i>
</span>
</div>
</div>
</div>
<div class="row">
<div class="col-xs-6">
<div class="input-group">
<input type="text" class="form-control"/>
<button class="input-group-addon" type="submit">
<i class="fa fa-search"></i>
</button>
</div>
</div>
</div>