In Blender 2.8 how do I mirror my weight painting? I am weight painting a human model and would like whatever I do to one half of the body be reflected in the other. In 2.7 it seems there was some sort of "mirror X" object but I don't see that option here in 2.8 (I should mention I just started with blender a few weeks ago and have no prior modeling experience whatsoever). 

I did find a "Mirror" option in the "Weights" section of weighpainting mode, but that just seems to swap the side I was working on with the other side...
Here it is as well, select the object with weights attached ( after automatic weight addition, the standard way - - Then click here, it's not under ' Symmetry ' but, under options, in this menu - -