<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<div class="container">
<div class="col-md-12">
<form class="form-horizontal form-label-left">
<fieldset class="custom-border">
<legend class="custom-border">Legend Label</legend>
<div class="form-group">
<div class="col-md-6">
<label>Input Field</label>
</div>
<div class="col-md-6">
<input type="text" class="form-control">
</div>
</div>
</fieldset>
</form>
</div>
</div>