As we are nearing Beta, meaning feature-complete, I would like to point out that this feature is not working. Or is it completely missing?
With the clipping border (Alt-B in Blender 2.79, but also in the new 2.8 keymap) , you can restrict the visibility in the 3D viewport to a smaller area/volume. This is great in complex scenes, with many objects, and objects inside other objects. You can also use it to make a simple 3D cutaway-view.
Does this have something to do with the Eevee viewport? Maybe it’s harder to make it work with Eevee? Even then it should still work in solid OpenGL view.