CMake: Linking statically against libgcc and libstdc++ into a shared library

Problem:

I am having difficulties linking glibcc/glibc++ into a shared library using CMake and GCC4.9 on my Ubuntu 16.04 installation.

Additional conditions:

Loading the shared library gives a problem om the Red Hat production environment(where I copy it to), I believe because it uses a different libstc++ version(error: GLIBCXX_3_4_20 not found). I do not have sudo rights and cannot upgrade the machine.

As I derived from this blog, this post, I tried linking static linking against libgcc and libgc++ using:

set(CMAKE_EXE_LINKER_FLAGS "-static-libgcc -static-libstdc++ -static")

and againg using

set(CMAKE_SHARED_LINKER_FLAGS "-static-libgcc -static-libstdc++ -static")

But that doesn't work. What does work is this CMake script:

add_library(myLib SHARED ${SOURCE_FILES})
set(CMAKE_EXE_LINKER_FLAGS " -static")
target_link_libraries(myLib -static-libgcc -static-libstdc++)

This must be the wrong way of doing this, to my knowledge -static-libgcc and -static-libstdc++ are linker options and not libraries...

Question: How do I link statically against -libgcc and -libstdc++ correctly?

Thanks in advance!