JQuery :: Set Property Based On Sibling Width()?

I'm trying to set a width of a span class based on the width of the image inside of it. I've got a container that will also have a bunch of images... some of them will have captions and will be wrapped in a class "caption"... some will not be wrapped in the "caption" class. I'm trying to loop through the container... find all the "caption" classes... and then set the width of the caption class based on the width of the image inside of it. Here's what a basic image with a caption will look like:

<span class="caption fltrt">
<img src="" alt="" />
caption goes here
</span>

I'm able to look through the containing div and locate all the images and then get their width using the following:

// Find all images in the overview section
var overviewImgs = $(".overview-content").find("img");
// Get the width of each image in the overview section

[code]....

I can't figure out how to loop through and find all the instances of "caption" and then set the width of the "caption" class based on the
width of the image inside of it.I can find all the "caption" classes... and I can find all the images and get the image widths... but I'm not sure how to combine these two so I am only finding the images inside of the "caption" class and then setting the "caption" class width based on the width of the image inside of it. The images are added by a separate content developer and can be any size. Not all images will have captions... only the ones wrapped in the "caption" class.