On Linux and macOS hosts, the LLVM toolchain will typically be installed via the package management tool provided by the Linux distribution or as part of the Xcode Command Line Tools and will be located on the system PATH. If your LLVM toolchain is not on the system PATH when launching the Eclipse Workbench, you may need to add the location of your LLVM binaries to the PATH environment variable within Eclipse. This is done by navigating to Window → Preferences → C/C++ → Build → Environment. Select the PATH environment variable and then edit its value to point where your LLVM binaries are located.

If your PATH environment variable is set correctly, you should see the LLVM with Clang and LLVM with GCC toolchains available for selection within the CDT project wizard for managed build projects. The toolchains are available for both C and C++ projects.