Dynamic languages rely on native extensions written in languages such as C/C++ or Fortran. To efficiently support the execution of native extensions in the multi-lingual GraalVM, we have implemented Sulong, which executes LLVM IR to support all languages that have a LLVM back end. It supports configurations with respect to memory-allocation and memory-access strategies that have different tradeoffs concerning safety and interoperability with native libraries. Sulong supports the execution of inline assembly for the most commonly used x86 instructions and GCC compiler builtins; it is complete enough to execute a complete libc.