llvm: How to get the call graph for a module of external node

I am having a program lets consider myProgram.c which uses some library (user created library) lets say myLibrary.

#include "myLibrary.h"'

int main()
{
    //call some function in myLibrary lets say foo
    foo();
}

Now when I have created a module pass. And I am generating call graph. Now in the call graph generated there is a node for the function foo() as follows:

Call graph node for function: ‘foo’<<0x951d300>> #uses=3 CS<0x0> calls external node.

Now I want all the functions which will be called by this foo in the “myLibrary”.

Is it possible? Can I get the call graph of myLibrary through the call graph node of the function foo in myProgram.c