Vanilla clang requires either -nogpulib or both --rocm-path and --rocm-device-lib-path flags
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -39,7 +39,7 @@ endmacro()
 macro(add_test_input_bitcode name input output)
   add_custom_command(
     OUTPUT "${output}"
-    COMMAND "$<TARGET_FILE:clang>" -c --offload-arch=gfx906 -emit-llvm -fgpu-rdc
+    COMMAND "$<TARGET_FILE:clang>" -c --offload-arch=gfx906 -emit-llvm -fgpu-rdc --rocm-path=@GENTOO_PORTAGE_EPREFIX@/usr --hip-device-lib-path=@GENTOO_PORTAGE_EPREFIX@/usr/lib/amdgcn/bitcode
     --gpu-bundle-output ${ARGN} "${CMAKE_CURRENT_SOURCE_DIR}/${input}"
     -o "${output}"
     VERBATIM