Get directory where cross file is located in cross file?

[xbjfk]

I am distributing toolchains and inside them there is a clang config file and CMake toolchain file. For clang I can use <CFGDIR>, and for CMake CMAKE_CURRENT_LIST_DIR. The idea is that a user can extract the toolchain to anywhere on their system, then specify --cross-file, and arguments like --sysroot and -resource-dir can be set relative to the direcory.
For example the clang config file looks like this, and the user specifies --config:

...
--sysroot=<CFGDIR>/../../..
-resource-dir <CFGDIR>/../../../lib/clang
...

or the CMake toolchain:

...
set(CMAKE_SYSROOT "${CMAKE_CURRENT_LIST_DIR}/../..")
...

Is there any way to do this in meson?