Building against Qt in /usr/lib64 (anything != $prefix/lib) with CMake fails

Qt adds wrong file paths into the linker call in CMake project builds:

[ 66s] c++: error: /usr/lib/libQt5Widgets.so: No such file or directory
[ 66s] c++: error: /usr/lib/libQt5Gui.so: No such file or directory
[ 66s] c++: error: /usr/lib/libQt5Core.so: No such file or directory
[ 66s] c++: error: /usr/lib/libQt5Widgets.so: No such file or directory
[ 66s] c++: error: /usr/lib/libQt5Gui.so: No such file or directory
[ 66s] c++: error: /usr/lib/libQt5Core.so: No such file or directory
[ 66s] c++: error: /usr/lib/libGL.so: No such file or directory

This seems to be because "/lib" is hardcoded in Qt5BasicConfig.cmake.in:

get_filename_component(_qt5_install_libs \"${_qt5$${CMAKE_MODULE_NAME}_install_prefix}/lib\" ABSOLUTE)