On macOS Sierra (10.12) and Xcode 8.0 (8A218a) When building the latest Rust, I fail during our LLVM build at: ``` [ 61%] Building CXX object lib/Analysis/CMakeFiles/LLVMAnalysis.dir/ValueTracking.cpp.o [ 61%] Building CXX object lib/Analysis/CMakeFiles/LLVMAnalysis.dir/VectorUtils.cpp.o [ 61%] Linking CXX static library ../libLLVMAnalysis.a [ 61%] Built target LLVMAnalysis make: *** [all] Error 2 thread 'main' panicked at ' command did not execute successfully, got: exit code: 2 ```