[llvm-dev] thumbv7 build errors "requires arm-mode"

[Steve King via llvm-dev]

After a recent upstream pull, my builds for ARM thumbv7 suddenly fail
with messages like:

error: instruction requires: arm-mode
 21         uxtah   r6, r0, r6

I use llc with -mtriple=thumbv7-unknown-unknown and llvm-mc with
-triple=thumbv7-unknown-unkown.

What's the right way to generate thumbv7 binaries?

Thanks,
-steve