c++ - OS X安装clang标准库libcxx错误？

在用户根目录下成功编译安装最新llvm-clang。
安装libcxx时出现错误。

svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx
成功。
在~/llvm-clang/libcxx/lib下执行
./buildit
报错

+ clang algorithm.o any.o bind.o chrono.o condition_variable.o debug.o exception.o future.o hash.o ios.o iostream.o locale.o memory.o mutex.o new.o optional.o random.o regex.o shared_mutex.o stdexcept.o string.o strstream.o system_error.o thread.o typeinfo.o utility.o valarray.o -fPIC -o libc++.so.1.0 -shared -nodefaultlibs -Wl,-soname,libc++.so.1 -lpthread -lrt -lc -lstdc++ -nostdinc++ -std=c++11 -fstrict-aliasing -Wall -Wextra -Wshadow -Wconversion -Wstrict-aliasing=2 -Wstrict-overflow=4
clang: warning: argument unused during compilation: '-nostdinc++'
ld: unknown option: -soname
clang: error: linker command failed with exit code 1 (use -v to see invocation)