llvm-ld does not support self-made library??

Hi There

I met a problem about llvm-ld.

First, I used the following command to create a llvm bitcode file add.o

clang -emit-llvm -c -o add.o add.c

Then, I tried the command to link add.o into a single llvm bitcode file add.

llvm-ld -o add add.o -ltrapub

libtrapub.so is a self-made shared library, however, llvm-ld always threw out the error message saying "Cannot find library 'trapub'", I tried many ways, including set 'LLVM_LIB_SEARCH_PATH', specify the directory via -L command as well as place the library under the current directory, they all did not work.

Any help is highly appreciated.