build static linked clang with gcc 4.8.3 on centos - gcc

Question

I'm trying to build a static linked executable clang on centos 6. I'm using gcc4.8.3 compiled from source.
If I compile with cmake option -DLLVM_BUILD_STATIC=ON, the error is:
CMake Error at cmake/modules/CheckAtomic.cmake:52 (message):
Host compiler appears to require libatomic, but cannot find it.
Call Stack (most recent call first):
cmake/config-ix.cmake:307 (include)
CMakeLists.txt:590 (include)
If I add -static flag to CMAKE_EXE_LINKER_FLAGS directly, the error is:
ld: dynamic STT_GNU_IFUNC symbol `strcmp' with pointer equality in
`/usr/lib/../lib64/libc.a(strcmp.o)' can not be used when making
an executable; recompile with -fPIE and relink with -pie
If I add -fPIE to CMAKE_CXX_FLAGS, and -Wl,-pie to CMAKE_EXE_LINKER_FLAGS directly, the error is:
CMake Error at cmake/modules/CheckAtomic.cmake:52 (message):
Host compiler appears to require libatomic, but cannot find it.
Call Stack (most recent call first):
cmake/config-ix.cmake:307 (include)
CMakeLists.txt:590 (include)
Checking the error message in llvm_build/CMakeFiles/CMakeError.log, I found cmake use the following code the check atomic.
#include <atomic>
std::atomic<float> x(0.0f);
int main() { return (float)x; }
The command to compile this code is:
/home/hailin/gcc-4.8.3-boost-1.55/rtf/bin/g++ -std=c++11 -fPIC -fPIE -Wl,-pie -DHAVE_CXX_ATOMICS_WITH_LIB -std=c++11 main.cpp
/home/hailin/gcc-4.8.3-boost-1.55/rtf/lib/gcc/x86_64-unknown-linux-gnu/4.8.3/../../../../x86_64-unknown-linux-gnu/bin/ld: /usr/lib/../lib64/crt1.o: relocation R_X86_64_32S against `__libc_csu_fini' can not be used when making a shared object; recompile with -fPIC
/usr/lib/../lib64/crt1.o: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
If I remove the flag -Wl,-pie, the error will gone.