It isn't going to be a holly. San Diego is too warm for hollies to grow. You are going to have to wait until it flowers to really tell what it is.

Ilex cornuta, I. x altaclarensis, I. x aquipernyi, and I. x meservae varieties do well there, but this doesn't look like any of these. What do the leaves feel like, Ben? Soft, or stiff and bristly? Do the older ones seem to be developing woody structure?