Add cancel link to all the form created in drupal site

Hi

I have assign a task to "Add cancel link to all the form used through out drupal site".
In my site there many forms, with submit and delete button.Now requirement says that i have to add cancel link to all the forms used through out my site.
It is hard to open each and every form and add a cancel link using hard code.
So what I want is that "Can we have any functionality which uses the form_id of each form and can add a cancel link code, which should get reflected in every form.

Note : When we click on cancel link the destination URL should be depend upon the previous URL from where the form is called.

If any body can help me! Do reply.

Thanks in Advance!