I got tired of looking at my phone sideways while it was propped up landscape wise, in my case.
1. Locate "build.prop" in /system using your favorite file explore
2. Open it up and at the bottom add the lines
Lockscreen rotation still not working for you???
A few users have reported that adding a blank line between the two, fixes this issue.
Once the phone reboots your lockscreen and Google Now launcher will rotate with the orientation of the device just like other apps do.
To undo this, simply remove the lines we added
enigma9o7 Has figured out how to get this to stick even after an update! Head over to his post for the walkthrough and install guide!! Remember to give them a "thanks" for sharing the work!