Ooh! Ooh! I finally know one of the songs someone is asking about... maybe. I'm not sure if this is what you're looking for, but "Little Molly" sorta fits as far as the subject goes, and when you actually sing it, "little" could get shortened to "li'l". On the other hand, I am a newbie and never heard of but a tiny fraction of the songs people talk about here, so there could well be some famous song called "Lil Mollie" that I never heard of -- but I'm so excited to finally know all the words to a song someone is asking about, that I'm going to post it anyway because I might never get another chance to sound all knowledgable 'n' stuff :)

Little Molly
There used to be a rover, he courted all around
There used to be a rover, he courted all around
He courted little Molly and her grave's never been found.

Little Molly, little Molly, come and go along with me
Little Molly, little Molly, come and go along with me
Before we get married, some pleasure for to see

Oh, Willie, oh, Willie, I'm afraid of your ways
Willie, oh, Willie! I'm afraid of your ways
I'm afraid you will lead my poor body astray

Molly, little Molly, you guessed just right
Molly, little Molly, you guessed just right
For I've dug on your grave the best part of last night

Willie, oh Willie, you fill my heart with fear
Willie, oh Willie, you fill my heart with fear
How can you mean harm to your own Molly dear?

Over the hills and the mountains they ride
Over the hills and the mountains they ride
And he took little Molly, and lay her by his side

Then he stabbed her in the heart and her heart's blood did flow
He stabbed her in the heart and her heart's blood did flow
And into the grave little Molly did go

He buried her deep and he strowed(?) the grave with thorns
He buried her deep and he strowed the grave with thorns
And left no one behind but the wild birds to mourn

Now a debt to the devil Willie must pay
A debt to the devil Willie must pay
For killing little Molly and hiding her away