# Individual preset options:
#
# 1. mixin-preset: building for Linux, without compiler assertions, and with
#    most tests disabled
# 2. build-ninja=0, libicu=0, skip-build-curl, skip-build-zlib: we'd prefer to
#    pick these up from the system
# 3. build-swift-libexec=0: don't build binaries normally installed in
#    `/usr/local/libexec` because we're not allowed to install there ourselves
# 4. extra-cmake-options:
#    * -DSWIFT_USE_LINKER=lld: let Swift know we'll be building it with `lld`
#    * -DBUILD_TESTING, -DSWIFT_INCLUDE_TESTS, -DSWIFT_INCLUDE_TEST_BINARIES:
#      the `no_test` preset disables building most, but not all tests; we don't
#      need to build any of them
#    * -DCOMPILER_RT_BUILD_ORC: the `compiler-rt` library defaults to building
#      the ORC LLVM JIT library, which we don't require; we disable it because
#      it builds with executable stacks, which trip up warnings on installation
#    * -DPython3_FIND_UNVERSIONED_NAMES: LLDB ships with Python bindings, and
#      uses CMake to search for Python. By default, CMake tries to find the
#      latest version installed on disk (currently, `python3.13`, then
#      `python3.12`, then...). This might not be the version of Python specified
#      by `PYTHON_SINGLE_TARGET`, which we want to respect. We use
#      `python_setup` to place `${EPYTHON}` at the front of `PATH` as the
#      unversioned `python3`, so we want CMake to discover and use this binary
#      first before falling back to its search
# 5. llvm-targets-to-build: we don't currently support architectures other than
#    amd64, so there's no point in building LLVM for multiple architectures; if
#    this changes (or we start supporting cross-compilation), we'll need to
#    build for more than just the host

--- a/swift/utils/build-presets.ini
+++ b/swift/utils/build-presets.ini
@@ -3051,3 +3051,24 @@ skip-test-cmark

 llvm-cmake-options=
   -DCLANG_DEFAULT_LINKER=gold
+
+[preset: gentoo]
+mixin-preset=buildbot_linux,no_assertions,no_test
+build-ninja=0
+extra-cmake-options=
+       -DLLVM_USE_LINKER:STRING=lld
+       -DBUILD_TESTING:BOOL=NO
+       -DSWIFT_INCLUDE_TESTS:BOOL=NO
+       -DSWIFT_INCLUDE_TEST_BINARIES:BOOL=NO
+       -DCOMPILER_RT_BUILD_ORC:BOOL=NO
+       -DPython3_FIND_UNVERSIONED_NAMES:STRING=FIRST
+llvm-targets-to-build=host
+skip-build-curl
+skip-build-zlib
+
+[preset: gentoo,libcxx]
+mixin-preset=gentoo
+libcxx
+llvm-cmake-options=
+       -DCLANG_DEFAULT_LINKER=lld
+       -DCLANG_DEFAULT_CXX_STDLIB=libc++