GOTO was supported in LLVM from the beginning.

The new feature is ASM GOTO. An ASM block is opaque to the compiler, and the compiler treats it similarly to a function call. A called function may contain control flow internal to itself, but can't cause control flow to happen in the caller. ASM GOTO is a new syntax for informing the compiler that this inline ASM may contain a GOTO to a given label. GCC added it around 4.5-ish, and LLVM is adding it in LLVM 9.

*FYI, the name for the thing that GOTO permits which combinations of if and loops doesn't is called "unstructured control flow".