<input type="password" autocomplete="off" />
The reason why the browser will prompt the user to save the password is that when type="password", the browser will pop up a prompt box, so the type cannot be set to password.
You can set the type to text, and then set the style attribute of this tag to -webkit-text-security:disc; so that the input text will become....)
<input type="text" style="-webkit-text-security:disc;" />