Techniques for cross-module in-lining are disclosed. In an embodiment, in-lining is done in conjunction with a 3-phase compiler including a front-end phase, an IPA (Inter-Procedural Analysis) phase, and a back-end phase. The front-end phase processes the source code in various modules and provides the intermediate representations of such source code. The IPA phase determines whether a function should be in-lined, and, if so, provides in-line transformation instructions for the back-end phase to execute. The back-end phase executes the instructions provided by the IPA, which, in effect, transforms the in-lining code.