For Blender 2.8 the Edit Mode feature Limit selection to visible, now referenced as Show whole scene transparent, has been updated. When active all Scene objects, in all interaction and editing modes and contexts, appear semi-transparent/semi-opaque, in other words back faces and anterior objects will be visible through the selected item in Object Mode or Weight Paint interaction mode as much as they were in Edit Mode previously.
Design note: Show whole scene transparent is not the same as using transparent materials.
To activate or enable Show whole scene transparent, click the icon  to the left of the ‘render’ buttons upper-right of the 3D View, or press the O key (letter ‘O’ not number ‘0’). The entire scene, and object within, will appear semi-transparent.
Design note: the level of transparency used by Show whole scene transparent is not immediately editable, a User Preferences option has not been provided to alter it.
Show whole scene transparent affects all interaction modes in a slightly different way depending on the mode but will generally display back faces and/or anterior objects regardless aiding the task being performed.