I attempted to compile Boost using clang and libc++. On x86, the LLVM target triple is x86_64-unknown-linux-gnu, It is the default installation locations for libc++'s header and library files. Clang will search for library files in this directories correctly based on the --target. However, when I tried to compile Boost using clang+libc++, the Boost build system forcibly passed --target=x86_64-pc-linux. This caused clang to fail to find the corresponding header and library files correctly.
use option to force boost build pass --target=x86_64-unknown-linux-gnu to clang