Sulong is an execution engine for LLVM bitcode and is part of GraalVM, a polyglot virtual machine that can execute programs written in multiple programming languages. Besides advanced tooling (e.g., debugging, monitoring and profiling), GraalVM supports cross-language interoperability as well, which includes languages that can be compiled to LLVM bitcode, such as Swift and C++. Although Sulong runs LLVM bitcode within GraalVM, the implemented interoperability concept also takes the corresponding source language (C++/Swift) semantics into account (e.g., where to apply dynamic binding). In this talk, we will show that Swift/C++ code can be used to treat objects from different languages the same way as Swift/C++ objects, and vice versa. Moreover, we will demonstrate how to use object-oriented concepts (such as interfaces and information hiding) across those languages.