problem building libclc

Dear Libclc Developers,

I have checked out the recent libclc and I encountered some problems
when building it. First of all, it looks like most recent clang
release does not support option "ccc-host-triple", which is "triple"
now. Secondly, there seems to be no target named nvptx--nvidia cl.
Instead, there is target nvptx, nvptx64. So I modified the configure
file, and when I tried make. I saw this error

./ptx-nvidiacl/lib/synchronization/ error: use of
unknown builtin '__builtin_ptx_bar_sync'

Here is the compilation command for this file:

clang -MMD -MF nvptx--nvidiacl/lib/synchronization/
-cc1 -triple nvptx-unknown-unknown
-I./ptx-nvidiacl/lib/synchronization -I./ptx-nvidiacl/include
-I./generic/include -Dcl_clang_storage_class_specifiers -Dcl_khr_fp64
-emit-llvm -c -o nvptx--nvidiacl/lib/synchronization/

Can anyone point me to some direction for resolving this issue?

Thanks a lot!