How to start padding outside an Image's Border and not inside?

I’m trying to add padding to the right of my images inserted to left align. My images have a border, so when I add padding, it works, but it adds a space between the image and border, instead of just padding to the right of the complete image. How can I get the padding to start outside the image’s border? This is the code I’m using:

.alignleft {
    float: left;
    border: 3px solid #111111;
}