How do I select the <li> element that is a direct parent of the anchor element?

As an example, my CSS would be something like this:

li < a.active {
    property: value;
}

Obviously there are ways of doing this with JavaScript, but I'm hoping that there is some sort of workaround that exists native to CSS Level 2.

The menu that I am trying to style is being spewed out by a CMS, so I can't move the active element to the <li> element... (unless I theme the menu creation module which I'd rather not do).

Any ideas?