Hi,
In a thread about making the default build use LLD over BFD to avoid out of RAM errors one of the solutions most people seem to like is to change the default CMAKE_BUILD_TYPE to Release over Debug since this would be a better default for most users building LLVM.
I have now posted a diff for this over at Phab: D124153 [CMake] Change default CMAKE_BUILD_TYPE to Release (llvm.org)
Please let me know if there are any concerns with this change.