Q: Changing Compiler to llvm-clang on existing iPhone Project When I switch the Compiler Version to Clang llvm 1.0 in existing projects I get the following build error when Precompiling the *.pch file:
error: can't exec '/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/llvm-gcc-4.2' (No such file or directory)

Is there another setting I need to change to get my project to work with the new compiler? 
(I did try a clean all targets)

Update:
To clarify:
Since the new compiler does in fact work with new projects, the issue is not that my system is missing anything.
Additionally, Xcode should not even be trying to find llvm-gcc-4.2 as the whole point is that I switched from that compiler to the new one, Clang llvm 1.0. This is what has led me to believe there is still another setting to be changed.

Thanks to fbereto for his suggestion. The actual answer lies in the comments.

A: If you look in path specified by the error you will not find an LLVM compiler (llvm-gcc-4.2) for the iPhone device:
/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/

That being said one does exist for the iPhone Simulator:
/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/

All this to say that while it may be possible to compile your iPhone App under LLVM for the Simulator, no equivalent tool exists for the device itself.
(Answer detailed in comments below.)
