About Shadow Stack

Dear All
I have a project in one of my courses in my master.
The project is to get rid of shadow stack of LLVM as it represents an overhead.
But I'm completely lost in this task.
My first question what is the alternative of shadow stack?
Any help is appreciated.

Regards,
Marwa Yusuf
Teaching Assistant - Computer Engineering Department
Faculty of Engineering - Benha University
E-JUST MSc Student
Computer Science & Engineering Dept.