How to link the externally generated objects in waf?

Question

I have a requirement where in I want to build the object files separately and link them together. Specifically I have a Makefile to build some objects which I want to call from the wscript file. I am able to call make command from the wscript file. But I am not able to figure out how to link these objects.

All the file contents are given below.

file1.c:

 #include <stdio.h> 

 extern void hello () ;

 int main ()
 {
    printf ("Hello file1\n") ;
    hello () ;
    return 0 ;  
 }

file2.c :

 #include <stdio.h> 

 void hello ()
 {
printf ("Hello file2\n") ;  
 }

Following are the contents of wscript file.

def options(opt):
    opt.load('compiler_c')

def configure(cnf):
    cnf.load('compiler_c')

def build(bld):
    bld(rule='cp ./../Makefile .')
    bld(rule='make', always='True')
    bld.program(features='c', 
    source=['file1.c'],
        includes=['build'],
    target='prog')  

Makefile:

CC = /usr/bin/gcc

file2.o:
$(CC) -c ./../file2.c -o ./file2.o 

Note : Beware of copying Makefile from here directly because of tabs.