JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-1.12.4.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.12.2/js/bootstrap-select.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.12.2/css/bootstrap-select.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<div class="container">
	<div class="page-header">
		<h1>
			Helloooo
			<span class="pull-right">
				<form method="post">
					<div class="form-group">
						<div class="input-group" id="el">
							<span class="input-group-addon"><span><i class="fa fa-bus"></i></span></span>
							<select class="form-control selectpicker">
								<option>aaaa</option>
								<option>bbbb bbbb</option>
								<option>cccc cccc cccc</option>
							</select>
						</div>
					</div>
				</form>
			</span>
		</h1>
	</div>
</div>

CSS

.input-group .bootstrap-select {
    width: auto !important;  /* Shrink width in IE */
}

.input-group .bootstrap-select > .btn {
    width: auto; /* Expand width in Firefox */
}

.page-header {
  display: inline-block;
}

#el{
  display: inline-block;
}

JavaScript

$(document).ready(function() {
			$('.selectpicker').selectpicker();
		});