Move {sys-libs → llvm-runtimes}/libcxx

Signed-off-by: Michał Górny <mgorny@gentoo.org>

18 files changed, 1680 insertions, 8 deletions

diff --git a/llvm-runtimes/libcxx/Manifest b/llvm-runtimes/libcxx/Manifest
new file mode 100644
index 000000000000..a4e227d59e17
--- /dev/null
+++ b/llvm-runtimes/libcxx/Manifest
@@ -0,0 +1,15 @@
+DIST llvm-gentoo-patchset-15.0.7-r1.tar.xz 21400 BLAKE2B 6b149cb721ac476b728bf9b0197f630d3db40622b85e3d099cdbc1d85ec14872d4e1eb0c94be6edc20fc6187da29b42f934dfb765f2077425a5b919900bb97c0 SHA512 d84d48caa3781633c7c6147e0b786417e93e4b5c9d1393809164e6d355a56673013ed0ea9bc3309488d7cfb794c1b336c888adc52dcd95e70c16d9208c36bd15
+DIST llvm-gentoo-patchset-16.0.6.tar.xz 17340 BLAKE2B 37cdf4b38367b4256d4f7a25d1b4f41758e5f81be8e20a1c94a10d6c5e36642e9672121b455e73a0bac2eb40467ef2db4b43789b2912a6790593d97b8b5c27e3 SHA512 2c02b9d8a4c5af9fddcd26c95dc66fffae32cb5b7f85c65a1aa4ed00dd8cd5b01cc1975a711aee63c0b8b11e9dc20f2bc05ea753904eb516892b820f02aff825
+DIST llvm-project-15.0.7.src.tar.xz 110936452 BLAKE2B f3d277e2029157329e5be78b78af36b0826a1dfd9a337992499bf701e33149665bfc47d5e14978e38f342559629a559f8b2ce328705ba34fdf6830f5ae9721a5 SHA512 4836d3603f32e8e54434cbfa8ef33d9d473ac5dc20ebf9c67132653c73f4524931abd1084655eaee5f20bcfcb91bcc4bbc5c4a0b603ad0c9029c556e14dc4c52
+DIST llvm-project-15.0.7.src.tar.xz.sig 566 BLAKE2B 47dc8c82d86237b80c6d85f83a6c9a6e9e174cf8e7f367b071e0cd9481d7cd408e991337c5624e07f3f370f26387c814f212808575ed1c1b58404d3e3836b7df SHA512 fc6891b440dd1175eb8df3790590af8d36bc92301660f84744ae15123475aeb900a151e6a8e7998ded27ec4d86871903ad0b89cd61164943054c2e3bc8d8beb2
+DIST llvm-project-16.0.6.src.tar.xz 118013488 BLAKE2B 95192d39cbd2914e5609db365965f1c00bfea6c2d653b3996bd2acef8a2b37e37f6fc8a9d2b65711ad72657e0ef52c42f733053cf65051e7822f27396c30406d SHA512 89a67ebfbbc764cc456e8825ecfa90707741f8835b1b2adffae0b227ab1fe5ca9cce75b0efaffc9ca8431cae528dc54fd838867a56a2b645344d9e82d19ab1b7
+DIST llvm-project-16.0.6.src.tar.xz.sig 566 BLAKE2B 2060cebd5ed57cb8a86a44238c43dfd4b921649298b10c3d19da308374c1e49869174294e29943c2af459fe06428264e26881d6c1288ebbc48686cc2cf467c7a SHA512 ca249262c7102e0889ec1bdc6f71a3a6f0e7e5d5fbab8abcd6fccd2871e7955eff7af5b055a76006097baf0dfaf2f5069eff3035b3107fc552abdb2481b21447
+DIST llvm-project-17.0.6.src.tar.xz 127838860 BLAKE2B d6ede1a9fda8756995c3e0654111941649e15794179641806f18919f1dc68c41ca0cabd5693b5096d05dccc3a391cd20d34af1137bf8af92ed3117a1ce84d1b2 SHA512 6d85bf749e0d77553cc215cbfa61cec4ac4f4f652847f56f946b6a892a99a5ea40b6ab8b39a9708a035001f007986941ccf17e4635260a8b0c1fa59e78d41e30
+DIST llvm-project-17.0.6.src.tar.xz.sig 438 BLAKE2B 186e75b6a0fbfe1e85408589c149e1800fcc47d685b74e4260018e05cd08bc793d1d1197c9c50e177eea941a3d0c65cb0c583ce6dae449099b920adf8a508ef7 SHA512 f78c55053a6450625f3e95f52c305110b4468a9854fec75831b65b8d6ceee3c9206ab9e63c4b5fda8be9bd344f72cfbdaae0520ed240abd505e08ebeaa25d340
+DIST llvm-project-18.1.8.src.tar.xz 132067260 BLAKE2B a950492f1dbfb874dff63b1ffef86468169ba2f211a9733ec2d4cf30040f7f277ef00f048bb44dee9f97d7d762f0f241f19e5a2a7b0b49217d3821ddfc8c354f SHA512 25eeee9984c8b4d0fbc240df90f33cbb000d3b0414baff5c8982beafcc5e59e7ef18f6f85d95b3a5f60cb3d4cd4f877c80487b5768bc21bc833f107698ad93db
+DIST llvm-project-18.1.8.src.tar.xz.sig 566 BLAKE2B 6ab0efc5b38d4483f4e32e8b85774b2edd5d88fdf29f23b88eb0b5130a7a7f0e80549612b025f927e92de4a08ff7c292cff224dbda91a5d598244e98f7ad0fbd SHA512 ddfd1e8a06756759af6cbe488c82a6d6a62ba91f3e8a0eb4cece561321824f5d165b08ed91010588790b76e19790931d2651b24dba8567e3b151d3cb43bec25b
+DIST llvm-project-19.1.4.src.tar.xz 141255156 BLAKE2B b99cd8a96e38dbcfb582ee5d2250268df36fb94fa0fd5b3611484094fbd7962051978334d2c623d2ff5a0209dbb2c6c6492be0146507ae982a7d3e9705a689c5 SHA512 a586f8a41dde5e0d9ca6d8c58e9ef2a2e59b70a86d2e2c46106dc31b5c096bb80af0cdbdb486179e9cc676a540099f49a1c2db9e5e84c50362db1f72e9af6906
+DIST llvm-project-19.1.4.src.tar.xz.sig 438 BLAKE2B b0925bdb761046d69779e0b035e29430bc09ef2b81be763aa5c853793631d7b7fdd65eb4dae7a1e3b4daa15d189c24cd1e14f065f79fdbf75429fa34be9b330e SHA512 3fb4a6c7594cb43680860698dac47062dde30de60f515dcecdad63812ea1edfb2cb209d0a7ac2254589c245a95b7c0f571b582e0d4b97a6ae8242563483ea764
+DIST llvm-project-19.1.5.src.tar.xz 141243716 BLAKE2B 228fc66ab688abfc16f31b2cd83163b81ef61604ace21eab69a1776f0dc88cbe8fa831162205849e5be3975a214136399572b4ad1b908986e37b2d38a1a7fa5d SHA512 648854e9c91fdcc5c677ce3800e046f2060b998a45cf9f7eebe02898431b3924f9348b6fc366102cd4fdda72dcb8f32076f98aa69927e0e20b3f1007fba10b22
+DIST llvm-project-19.1.5.src.tar.xz.sig 438 BLAKE2B 1d40a5c5405f99ef86e3360f9ea153afd1ae4001697210fd799a988113e8a3cef39e2c4794edd9332f384d8490f4ce2ab6bee6d98f794f84775807f833b81c0a SHA512 a438c86ce882eb1ac3e50842937068794ed162bb1b7ded68a2fe3ec2ab4f57cc38aee667cfb46afe6da22eef7ed1cb65820a473f63bd5a0dc6aad41df7bfad54
+DIST llvm-project-32f7f0010bca99ee4bd917f57272733fb2bf3bd9.tar.gz 223983502 BLAKE2B fd3e6b0b795abc42568ef98fa774d927029c18838a5d0f34eaa66c37976444a63f2fc5d883f3bf3a98533f51e387936f1c659230f31c757d26153425696a16cd SHA512 65a345ad5b77c627008f759947e5e9f28a62c8992d7146113e0446e5849feaf9088c15c8b22ca0824af5b927d6a417f5326258b489fb8ccea78ec9e0e0fe8fba
diff --git a/llvm-runtimes/libcxx/libcxx-15.0.7-r1.ebuild b/llvm-runtimes/libcxx/libcxx-15.0.7-r1.ebuild
new file mode 100644
index 000000000000..429e5f596920
--- /dev/null
+++ b/llvm-runtimes/libcxx/libcxx-15.0.7-r1.ebuild
@@ -0,0 +1,204 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..11} )
+inherit cmake-multilib flag-o-matic llvm llvm.org python-any-r1 \
+	toolchain-funcs
+
+DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+KEYWORDS="amd64 arm arm64 ~riscv sparc x86 ~x64-macos"
+IUSE="+clang +libcxxabi +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	libcxxabi? (
+		~llvm-runtimes/libcxxabi-${PV}[static-libs?,${MULTILIB_USEDEP}]
+	)
+	!libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		dev-debug/gdb[python]
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=( runtimes libcxx{,abi} llvm/{cmake,utils/llvm-lit} cmake )
+LLVM_PATCHSET=${PV}-r1
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	# Darwin Prefix builds do not have llvm installed yet, so rely on
+	# bootstrap-prefix to set the appropriate path vars to LLVM instead
+	# of using llvm_pkg_setup.
+	if [[ ${CHOST} != *-darwin* ]] || has_version sys-devel/llvm; then
+		LLVM_MAX_SLOT=${LLVM_MAJOR} llvm_pkg_setup
+	fi
+	python-any-r1_pkg_setup
+
+	if ! use libcxxabi && ! tc-is-gcc ; then
+		eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+		eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+		eerror "and try again."
+		die
+	fi
+}
+
+test_compiler() {
+	$(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	# note: we need to do this before multilib kicks in since it will
+	# alter the CHOST
+	local cxxabi cxxabi_incs
+	if use libcxxabi; then
+		cxxabi=system-libcxxabi
+		cxxabi_incs="${EPREFIX}/usr/include/c++/v1"
+	else
+		local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+		cxxabi=libsupc++
+		cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+	fi
+
+	multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# bootstrap: cmake is unhappy if compiler can't link to stdlib
+	local nolib_flags=( -nodefaultlibs -lc )
+	if ! test_compiler; then
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES=libcxx
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXX_CXX_ABI=${cxxabi}
+		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+		# we're using our own mechanism for generating linker scripts
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=$(usex test)
+		-DLIBCXX_USE_COMPILER_RT=${use_compiler_rt}
+	)
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_src_compile
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		gen_shared_ldscript
+		use static-libs && gen_static_ldscript
+	fi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-cxx
+}
+
+multilib_src_install() {
+	cmake_src_install
+	# since we've replaced libc++.{a,so} with ldscripts, now we have to
+	# install the extra symlinks
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		dolib.so lib/libc++_shared.so
+		use static-libs && dolib.a lib/libc++_static.a
+	fi
+}
+
+# Usage: deps
+gen_ldscript() {
+	local output_format
+	output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+	[[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+	cat <<-END_LDSCRIPT
+/* GNU ld script
+   Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_static}.a || die
+	# Generate libc++.a ldscript for inclusion of its dependencies so that
+	# clang++ -stdlib=libc++ -static works out of the box.
+	local deps=(
+		libc++_static.a
+		$(usex libcxxabi libc++abi.a libsupc++.a)
+	)
+	# On Linux/glibc it does not link without libpthread or libdl. It is
+	# fine on FreeBSD.
+	use elibc_glibc && deps+=( libpthread.a libdl.a )
+
+	gen_ldscript "${deps[*]}" > lib/libc++.a || die
+}
+
+gen_shared_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_shared}.so || die
+	local deps=(
+		libc++_shared.so
+		# libsupc++ doesn't have a shared version
+		$(usex libcxxabi libc++abi.so libsupc++.a)
+	)
+
+	gen_ldscript "${deps[*]}" > lib/libc++.so || die
+}
diff --git a/llvm-runtimes/libcxx/libcxx-16.0.6.ebuild b/llvm-runtimes/libcxx/libcxx-16.0.6.ebuild
new file mode 100644
index 000000000000..e66a304bab88
--- /dev/null
+++ b/llvm-runtimes/libcxx/libcxx-16.0.6.ebuild
@@ -0,0 +1,204 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..12} )
+inherit cmake-multilib flag-o-matic llvm llvm.org python-any-r1 \
+	toolchain-funcs
+
+DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+KEYWORDS="amd64 arm arm64 ~loong ~riscv sparc x86 ~arm64-macos ~x64-macos"
+IUSE="+clang +libcxxabi +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	libcxxabi? (
+		~llvm-runtimes/libcxxabi-${PV}[static-libs?,${MULTILIB_USEDEP}]
+	)
+	!libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		dev-debug/gdb[python]
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=( runtimes libcxx{,abi} llvm/{cmake,utils/llvm-lit} cmake )
+LLVM_PATCHSET=${PV}
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	# Darwin Prefix builds do not have llvm installed yet, so rely on
+	# bootstrap-prefix to set the appropriate path vars to LLVM instead
+	# of using llvm_pkg_setup.
+	if [[ ${CHOST} != *-darwin* ]] || has_version sys-devel/llvm; then
+		LLVM_MAX_SLOT=${LLVM_MAJOR} llvm_pkg_setup
+	fi
+	python-any-r1_pkg_setup
+
+	if ! use libcxxabi && ! tc-is-gcc ; then
+		eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+		eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+		eerror "and try again."
+		die
+	fi
+}
+
+test_compiler() {
+	$(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	# note: we need to do this before multilib kicks in since it will
+	# alter the CHOST
+	local cxxabi cxxabi_incs
+	if use libcxxabi; then
+		cxxabi=system-libcxxabi
+		cxxabi_incs="${EPREFIX}/usr/include/c++/v1"
+	else
+		local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+		cxxabi=libsupc++
+		cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+	fi
+
+	multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# bootstrap: cmake is unhappy if compiler can't link to stdlib
+	local nolib_flags=( -nodefaultlibs -lc )
+	if ! test_compiler; then
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES=libcxx
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXX_CXX_ABI=${cxxabi}
+		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+		# we're using our own mechanism for generating linker scripts
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=$(usex test)
+		-DLIBCXX_USE_COMPILER_RT=${use_compiler_rt}
+	)
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_src_compile
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		gen_shared_ldscript
+		use static-libs && gen_static_ldscript
+	fi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-cxx
+}
+
+multilib_src_install() {
+	cmake_src_install
+	# since we've replaced libc++.{a,so} with ldscripts, now we have to
+	# install the extra symlinks
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		dolib.so lib/libc++_shared.so
+		use static-libs && dolib.a lib/libc++_static.a
+	fi
+}
+
+# Usage: deps
+gen_ldscript() {
+	local output_format
+	output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+	[[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+	cat <<-END_LDSCRIPT
+/* GNU ld script
+   Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_static}.a || die
+	# Generate libc++.a ldscript for inclusion of its dependencies so that
+	# clang++ -stdlib=libc++ -static works out of the box.
+	local deps=(
+		libc++_static.a
+		$(usex libcxxabi libc++abi.a libsupc++.a)
+	)
+	# On Linux/glibc it does not link without libpthread or libdl. It is
+	# fine on FreeBSD.
+	use elibc_glibc && deps+=( libpthread.a libdl.a )
+
+	gen_ldscript "${deps[*]}" > lib/libc++.a || die
+}
+
+gen_shared_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_shared}.so || die
+	local deps=(
+		libc++_shared.so
+		# libsupc++ doesn't have a shared version
+		$(usex libcxxabi libc++abi.so libsupc++.a)
+	)
+
+	gen_ldscript "${deps[*]}" > lib/libc++.so || die
+}
diff --git a/llvm-runtimes/libcxx/libcxx-17.0.6.ebuild b/llvm-runtimes/libcxx/libcxx-17.0.6.ebuild
new file mode 100644
index 000000000000..044e5553e75c
--- /dev/null
+++ b/llvm-runtimes/libcxx/libcxx-17.0.6.ebuild
@@ -0,0 +1,203 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..12} )
+inherit cmake-multilib flag-o-matic llvm llvm.org python-any-r1 \
+	toolchain-funcs
+
+DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+KEYWORDS="amd64 arm arm64 ~loong ~riscv sparc x86 ~arm64-macos ~x64-macos"
+IUSE="+clang +libcxxabi +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	libcxxabi? (
+		~llvm-runtimes/libcxxabi-${PV}[static-libs?,${MULTILIB_USEDEP}]
+	)
+	!libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		dev-debug/gdb[python]
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=( runtimes libcxx{,abi} llvm/{cmake,utils/llvm-lit} cmake )
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	# Darwin Prefix builds do not have llvm installed yet, so rely on
+	# bootstrap-prefix to set the appropriate path vars to LLVM instead
+	# of using llvm_pkg_setup.
+	if [[ ${CHOST} != *-darwin* ]] || has_version sys-devel/llvm; then
+		LLVM_MAX_SLOT=${LLVM_MAJOR} llvm_pkg_setup
+	fi
+	python-any-r1_pkg_setup
+
+	if ! use libcxxabi && ! tc-is-gcc ; then
+		eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+		eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+		eerror "and try again."
+		die
+	fi
+}
+
+test_compiler() {
+	$(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	# note: we need to do this before multilib kicks in since it will
+	# alter the CHOST
+	local cxxabi cxxabi_incs
+	if use libcxxabi; then
+		cxxabi=system-libcxxabi
+		cxxabi_incs="${EPREFIX}/usr/include/c++/v1"
+	else
+		local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+		cxxabi=libsupc++
+		cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+	fi
+
+	multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# bootstrap: cmake is unhappy if compiler can't link to stdlib
+	local nolib_flags=( -nodefaultlibs -lc )
+	if ! test_compiler; then
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES=libcxx
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXX_CXX_ABI=${cxxabi}
+		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+		# we're using our own mechanism for generating linker scripts
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=$(usex test)
+		-DLIBCXX_USE_COMPILER_RT=${use_compiler_rt}
+	)
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_src_compile
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		gen_shared_ldscript
+		use static-libs && gen_static_ldscript
+	fi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-cxx
+}
+
+multilib_src_install() {
+	cmake_src_install
+	# since we've replaced libc++.{a,so} with ldscripts, now we have to
+	# install the extra symlinks
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		dolib.so lib/libc++_shared.so
+		use static-libs && dolib.a lib/libc++_static.a
+	fi
+}
+
+# Usage: deps
+gen_ldscript() {
+	local output_format
+	output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+	[[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+	cat <<-END_LDSCRIPT
+/* GNU ld script
+   Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_static}.a || die
+	# Generate libc++.a ldscript for inclusion of its dependencies so that
+	# clang++ -stdlib=libc++ -static works out of the box.
+	local deps=(
+		libc++_static.a
+		$(usex libcxxabi libc++abi.a libsupc++.a)
+	)
+	# On Linux/glibc it does not link without libpthread or libdl. It is
+	# fine on FreeBSD.
+	use elibc_glibc && deps+=( libpthread.a libdl.a )
+
+	gen_ldscript "${deps[*]}" > lib/libc++.a || die
+}
+
+gen_shared_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_shared}.so || die
+	local deps=(
+		libc++_shared.so
+		# libsupc++ doesn't have a shared version
+		$(usex libcxxabi libc++abi.so libsupc++.a)
+	)
+
+	gen_ldscript "${deps[*]}" > lib/libc++.so || die
+}
diff --git a/llvm-runtimes/libcxx/libcxx-18.1.8.ebuild b/llvm-runtimes/libcxx/libcxx-18.1.8.ebuild
new file mode 100644
index 000000000000..8cc099018bca
--- /dev/null
+++ b/llvm-runtimes/libcxx/libcxx-18.1.8.ebuild
@@ -0,0 +1,210 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..12} )
+inherit cmake-multilib flag-o-matic llvm.org llvm-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+KEYWORDS="amd64 arm arm64 ~loong ~riscv sparc x86 ~arm64-macos ~x64-macos"
+IUSE="+clang +libcxxabi +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	libcxxabi? (
+		~llvm-runtimes/libcxxabi-${PV}[static-libs?,${MULTILIB_USEDEP}]
+	)
+	!libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		dev-debug/gdb[python]
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=( runtimes libcxx{,abi} llvm/{cmake,utils/llvm-lit} cmake )
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	python-any-r1_pkg_setup
+
+	if ! use libcxxabi && ! tc-is-gcc ; then
+		eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+		eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+		eerror "and try again."
+		die
+	fi
+}
+
+src_prepare() {
+	# hanging tests
+	# https://github.com/llvm/llvm-project/issues/73791
+	rm ../libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_* || die
+	rm ../libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.*_equals* || die
+
+	cmake_src_prepare
+}
+
+test_compiler() {
+	$(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# note: we need to do this before multilib kicks in since it will
+	# alter the CHOST
+	local cxxabi cxxabi_incs
+	if use libcxxabi; then
+		cxxabi=system-libcxxabi
+		cxxabi_incs="${EPREFIX}/usr/include/c++/v1"
+	else
+		local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+		cxxabi=libsupc++
+		cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+	fi
+
+	multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# bootstrap: cmake is unhappy if compiler can't link to stdlib
+	local nolib_flags=( -nodefaultlibs -lc )
+	if ! test_compiler; then
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES=libcxx
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXX_CXX_ABI=${cxxabi}
+		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+		# we're using our own mechanism for generating linker scripts
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=$(usex test)
+		-DLIBCXX_USE_COMPILER_RT=${use_compiler_rt}
+		# this is broken with standalone builds, and also meaningless
+		-DLIBCXXABI_USE_LLVM_UNWINDER=OFF
+	)
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_src_compile
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		gen_shared_ldscript
+		use static-libs && gen_static_ldscript
+	fi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-cxx
+}
+
+multilib_src_install() {
+	cmake_src_install
+	# since we've replaced libc++.{a,so} with ldscripts, now we have to
+	# install the extra symlinks
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		dolib.so lib/libc++_shared.so
+		use static-libs && dolib.a lib/libc++_static.a
+	fi
+}
+
+# Usage: deps
+gen_ldscript() {
+	local output_format
+	output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+	[[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+	cat <<-END_LDSCRIPT
+/* GNU ld script
+   Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_static}.a || die
+	# Generate libc++.a ldscript for inclusion of its dependencies so that
+	# clang++ -stdlib=libc++ -static works out of the box.
+	local deps=(
+		libc++_static.a
+		$(usex libcxxabi libc++abi.a libsupc++.a)
+	)
+	# On Linux/glibc it does not link without libpthread or libdl. It is
+	# fine on FreeBSD.
+	use elibc_glibc && deps+=( libpthread.a libdl.a )
+
+	gen_ldscript "${deps[*]}" > lib/libc++.a || die
+}
+
+gen_shared_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_shared}.so || die
+	local deps=(
+		libc++_shared.so
+		# libsupc++ doesn't have a shared version
+		$(usex libcxxabi libc++abi.so libsupc++.a)
+	)
+
+	gen_ldscript "${deps[*]}" > lib/libc++.so || die
+}
diff --git a/llvm-runtimes/libcxx/libcxx-19.1.4.ebuild b/llvm-runtimes/libcxx/libcxx-19.1.4.ebuild
new file mode 100644
index 000000000000..ef26774b58e0
--- /dev/null
+++ b/llvm-runtimes/libcxx/libcxx-19.1.4.ebuild
@@ -0,0 +1,202 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake-multilib flag-o-matic llvm.org llvm-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+KEYWORDS="amd64 arm arm64 ~loong ~riscv sparc x86 ~arm64-macos ~x64-macos"
+IUSE="+clang +libcxxabi +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	libcxxabi? (
+		~llvm-runtimes/libcxxabi-${PV}[static-libs?,${MULTILIB_USEDEP}]
+	)
+	!libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		dev-debug/gdb[python]
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=( runtimes libcxx{,abi} llvm/{cmake,utils/llvm-lit} cmake )
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	python-any-r1_pkg_setup
+
+	if ! use libcxxabi && ! tc-is-gcc ; then
+		eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+		eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+		eerror "and try again."
+		die
+	fi
+}
+
+test_compiler() {
+	$(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# note: we need to do this before multilib kicks in since it will
+	# alter the CHOST
+	local cxxabi cxxabi_incs
+	if use libcxxabi; then
+		cxxabi=system-libcxxabi
+		cxxabi_incs="${EPREFIX}/usr/include/c++/v1"
+	else
+		local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+		cxxabi=libsupc++
+		cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+	fi
+
+	multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# bootstrap: cmake is unhappy if compiler can't link to stdlib
+	local nolib_flags=( -nodefaultlibs -lc )
+	if ! test_compiler; then
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES=libcxx
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXX_CXX_ABI=${cxxabi}
+		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+		# we're using our own mechanism for generating linker scripts
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=$(usex test)
+		-DLIBCXX_INSTALL_MODULES=ON
+		-DLIBCXX_USE_COMPILER_RT=${use_compiler_rt}
+		# this is broken with standalone builds, and also meaningless
+		-DLIBCXXABI_USE_LLVM_UNWINDER=OFF
+	)
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_src_compile
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		gen_shared_ldscript
+		use static-libs && gen_static_ldscript
+	fi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-cxx
+}
+
+multilib_src_install() {
+	cmake_src_install
+	# since we've replaced libc++.{a,so} with ldscripts, now we have to
+	# install the extra symlinks
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		dolib.so lib/libc++_shared.so
+		use static-libs && dolib.a lib/libc++_static.a
+	fi
+}
+
+# Usage: deps
+gen_ldscript() {
+	local output_format
+	output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+	[[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+	cat <<-END_LDSCRIPT
+/* GNU ld script
+   Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_static}.a || die
+	# Generate libc++.a ldscript for inclusion of its dependencies so that
+	# clang++ -stdlib=libc++ -static works out of the box.
+	local deps=(
+		libc++_static.a
+		$(usex libcxxabi libc++abi.a libsupc++.a)
+	)
+	# On Linux/glibc it does not link without libpthread or libdl. It is
+	# fine on FreeBSD.
+	use elibc_glibc && deps+=( libpthread.a libdl.a )
+
+	gen_ldscript "${deps[*]}" > lib/libc++.a || die
+}
+
+gen_shared_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_shared}.so || die
+	local deps=(
+		libc++_shared.so
+		# libsupc++ doesn't have a shared version
+		$(usex libcxxabi libc++abi.so libsupc++.a)
+	)
+
+	gen_ldscript "${deps[*]}" > lib/libc++.so || die
+}
diff --git a/llvm-runtimes/libcxx/libcxx-19.1.5.ebuild b/llvm-runtimes/libcxx/libcxx-19.1.5.ebuild
new file mode 100644
index 000000000000..b6a85d925747
--- /dev/null
+++ b/llvm-runtimes/libcxx/libcxx-19.1.5.ebuild
@@ -0,0 +1,202 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake-multilib flag-o-matic llvm.org llvm-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+KEYWORDS="~amd64 ~arm ~arm64 ~loong ~riscv ~sparc ~x86 ~arm64-macos ~x64-macos"
+IUSE="+clang +libcxxabi +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	libcxxabi? (
+		~llvm-runtimes/libcxxabi-${PV}[static-libs?,${MULTILIB_USEDEP}]
+	)
+	!libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		dev-debug/gdb[python]
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=( runtimes libcxx{,abi} llvm/{cmake,utils/llvm-lit} cmake )
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	python-any-r1_pkg_setup
+
+	if ! use libcxxabi && ! tc-is-gcc ; then
+		eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+		eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+		eerror "and try again."
+		die
+	fi
+}
+
+test_compiler() {
+	$(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# note: we need to do this before multilib kicks in since it will
+	# alter the CHOST
+	local cxxabi cxxabi_incs
+	if use libcxxabi; then
+		cxxabi=system-libcxxabi
+		cxxabi_incs="${EPREFIX}/usr/include/c++/v1"
+	else
+		local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+		cxxabi=libsupc++
+		cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+	fi
+
+	multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# bootstrap: cmake is unhappy if compiler can't link to stdlib
+	local nolib_flags=( -nodefaultlibs -lc )
+	if ! test_compiler; then
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES=libcxx
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXX_CXX_ABI=${cxxabi}
+		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+		# we're using our own mechanism for generating linker scripts
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=$(usex test)
+		-DLIBCXX_INSTALL_MODULES=ON
+		-DLIBCXX_USE_COMPILER_RT=${use_compiler_rt}
+		# this is broken with standalone builds, and also meaningless
+		-DLIBCXXABI_USE_LLVM_UNWINDER=OFF
+	)
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_src_compile
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		gen_shared_ldscript
+		use static-libs && gen_static_ldscript
+	fi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-cxx
+}
+
+multilib_src_install() {
+	cmake_src_install
+	# since we've replaced libc++.{a,so} with ldscripts, now we have to
+	# install the extra symlinks
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		dolib.so lib/libc++_shared.so
+		use static-libs && dolib.a lib/libc++_static.a
+	fi
+}
+
+# Usage: deps
+gen_ldscript() {
+	local output_format
+	output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+	[[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+	cat <<-END_LDSCRIPT
+/* GNU ld script
+   Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_static}.a || die
+	# Generate libc++.a ldscript for inclusion of its dependencies so that
+	# clang++ -stdlib=libc++ -static works out of the box.
+	local deps=(
+		libc++_static.a
+		$(usex libcxxabi libc++abi.a libsupc++.a)
+	)
+	# On Linux/glibc it does not link without libpthread or libdl. It is
+	# fine on FreeBSD.
+	use elibc_glibc && deps+=( libpthread.a libdl.a )
+
+	gen_ldscript "${deps[*]}" > lib/libc++.a || die
+}
+
+gen_shared_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_shared}.so || die
+	local deps=(
+		libc++_shared.so
+		# libsupc++ doesn't have a shared version
+		$(usex libcxxabi libc++abi.so libsupc++.a)
+	)
+
+	gen_ldscript "${deps[*]}" > lib/libc++.so || die
+}
diff --git a/llvm-runtimes/libcxx/libcxx-20.0.0.9999.ebuild b/llvm-runtimes/libcxx/libcxx-20.0.0.9999.ebuild
new file mode 100644
index 000000000000..c39257020ea3
--- /dev/null
+++ b/llvm-runtimes/libcxx/libcxx-20.0.0.9999.ebuild
@@ -0,0 +1,208 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake-multilib flag-o-matic llvm.org llvm-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+IUSE="+clang +libcxxabi +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	libcxxabi? (
+		~llvm-runtimes/libcxxabi-${PV}[static-libs?,${MULTILIB_USEDEP}]
+	)
+	!libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		dev-debug/gdb[python]
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=(
+	runtimes libcxx{,abi} libc llvm/{cmake,utils/llvm-lit} cmake
+)
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	python-any-r1_pkg_setup
+
+	if ! use libcxxabi && ! tc-is-gcc ; then
+		eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+		eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+		eerror "and try again."
+		die
+	fi
+}
+
+test_compiler() {
+	$(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# note: we need to do this before multilib kicks in since it will
+	# alter the CHOST
+	local cxxabi cxxabi_incs
+	if use libcxxabi; then
+		cxxabi=system-libcxxabi
+		cxxabi_incs="${EPREFIX}/usr/include/c++/v1"
+	else
+		local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+		cxxabi=libsupc++
+		cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+	fi
+
+	multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# bootstrap: cmake is unhappy if compiler can't link to stdlib
+	local nolib_flags=( -nodefaultlibs -lc )
+	if ! test_compiler; then
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES=libcxx
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXX_CXX_ABI=${cxxabi}
+		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+		# we're using our own mechanism for generating linker scripts
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=$(usex test)
+		-DLIBCXX_INSTALL_MODULES=ON
+		-DLIBCXX_USE_COMPILER_RT=${use_compiler_rt}
+		# this is broken with standalone builds, and also meaningless
+		-DLIBCXXABI_USE_LLVM_UNWINDER=OFF
+	)
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_src_compile
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		gen_shared_ldscript
+		use static-libs && gen_static_ldscript
+	fi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build install-cxx-test-suite-prefix
+	cp "${BUILD_DIR}"/{lib,libcxx/test-suite-install/$(get_libdir)}/libc++_shared.so || die
+	if use static-libs; then
+		cp "${BUILD_DIR}"/{lib,libcxx/test-suite-install/$(get_libdir)}/libc++_static.a || die
+	fi
+	cmake_build check-cxx
+}
+
+multilib_src_install() {
+	cmake_src_install
+	# since we've replaced libc++.{a,so} with ldscripts, now we have to
+	# install the extra symlinks
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		dolib.so lib/libc++_shared.so
+		use static-libs && dolib.a lib/libc++_static.a
+	fi
+}
+
+# Usage: deps
+gen_ldscript() {
+	local output_format
+	output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+	[[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+	cat <<-END_LDSCRIPT
+/* GNU ld script
+   Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_static}.a || die
+	# Generate libc++.a ldscript for inclusion of its dependencies so that
+	# clang++ -stdlib=libc++ -static works out of the box.
+	local deps=(
+		libc++_static.a
+		$(usex libcxxabi libc++abi.a libsupc++.a)
+	)
+	# On Linux/glibc it does not link without libpthread or libdl. It is
+	# fine on FreeBSD.
+	use elibc_glibc && deps+=( libpthread.a libdl.a )
+
+	gen_ldscript "${deps[*]}" > lib/libc++.a || die
+}
+
+gen_shared_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_shared}.so || die
+	local deps=(
+		libc++_shared.so
+		# libsupc++ doesn't have a shared version
+		$(usex libcxxabi libc++abi.so libsupc++.a)
+	)
+
+	gen_ldscript "${deps[*]}" > lib/libc++.so || die
+}
diff --git a/llvm-runtimes/libcxx/libcxx-20.0.0_pre20241207.ebuild b/llvm-runtimes/libcxx/libcxx-20.0.0_pre20241207.ebuild
new file mode 100644
index 000000000000..c39257020ea3
--- /dev/null
+++ b/llvm-runtimes/libcxx/libcxx-20.0.0_pre20241207.ebuild
@@ -0,0 +1,208 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..13} )
+inherit cmake-multilib flag-o-matic llvm.org llvm-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
+HOMEPAGE="https://libcxx.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions || ( UoI-NCSA MIT )"
+SLOT="0"
+IUSE="+clang +libcxxabi +static-libs test"
+REQUIRED_USE="test? ( clang )"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	libcxxabi? (
+		~llvm-runtimes/libcxxabi-${PV}[static-libs?,${MULTILIB_USEDEP}]
+	)
+	!libcxxabi? ( >=sys-devel/gcc-4.7:=[cxx] )
+"
+DEPEND="
+	${RDEPEND}
+	sys-devel/llvm:${LLVM_MAJOR}
+"
+BDEPEND="
+	clang? (
+		sys-devel/clang:${LLVM_MAJOR}
+	)
+	!test? (
+		${PYTHON_DEPS}
+	)
+	test? (
+		dev-debug/gdb[python]
+		$(python_gen_any_dep 'dev-python/lit[${PYTHON_USEDEP}]')
+	)
+"
+
+LLVM_COMPONENTS=(
+	runtimes libcxx{,abi} libc llvm/{cmake,utils/llvm-lit} cmake
+)
+llvm.org_set_globals
+
+python_check_deps() {
+	use test || return 0
+	python_has_version "dev-python/lit[${PYTHON_USEDEP}]"
+}
+
+pkg_setup() {
+	python-any-r1_pkg_setup
+
+	if ! use libcxxabi && ! tc-is-gcc ; then
+		eerror "To build ${PN} against libsupc++, you have to use gcc. Other"
+		eerror "compilers are not supported. Please set CC=gcc and CXX=g++"
+		eerror "and try again."
+		die
+	fi
+}
+
+test_compiler() {
+	$(tc-getCXX) ${CXXFLAGS} ${LDFLAGS} "${@}" -o /dev/null -x c++ - \
+		<<<'int main() { return 0; }' &>/dev/null
+}
+
+src_configure() {
+	llvm_prepend_path "${LLVM_MAJOR}"
+
+	# note: we need to do this before multilib kicks in since it will
+	# alter the CHOST
+	local cxxabi cxxabi_incs
+	if use libcxxabi; then
+		cxxabi=system-libcxxabi
+		cxxabi_incs="${EPREFIX}/usr/include/c++/v1"
+	else
+		local gcc_inc="${EPREFIX}/usr/lib/gcc/${CHOST}/$(gcc-fullversion)/include/g++-v$(gcc-major-version)"
+		cxxabi=libsupc++
+		cxxabi_incs="${gcc_inc};${gcc_inc}/${CHOST}"
+	fi
+
+	multilib-minimal_src_configure
+}
+
+multilib_src_configure() {
+	if use clang; then
+		local -x CC=${CHOST}-clang
+		local -x CXX=${CHOST}-clang++
+		strip-unsupported-flags
+	fi
+
+	# link to compiler-rt
+	local use_compiler_rt=OFF
+	[[ $(tc-get-c-rtlib) == compiler-rt ]] && use_compiler_rt=ON
+
+	# bootstrap: cmake is unhappy if compiler can't link to stdlib
+	local nolib_flags=( -nodefaultlibs -lc )
+	if ! test_compiler; then
+		if test_compiler "${nolib_flags[@]}"; then
+			local -x LDFLAGS="${LDFLAGS} ${nolib_flags[*]}"
+			ewarn "${CXX} seems to lack runtime, trying with ${nolib_flags[*]}"
+		fi
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		-DCMAKE_CXX_COMPILER_TARGET="${CHOST}"
+		-DPython3_EXECUTABLE="${PYTHON}"
+		-DLLVM_ENABLE_RUNTIMES=libcxx
+		-DLLVM_INCLUDE_TESTS=OFF
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DLIBCXX_ENABLE_SHARED=ON
+		-DLIBCXX_ENABLE_STATIC=$(usex static-libs)
+		-DLIBCXX_CXX_ABI=${cxxabi}
+		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=${cxxabi_incs}
+		# we're using our own mechanism for generating linker scripts
+		-DLIBCXX_ENABLE_ABI_LINKER_SCRIPT=OFF
+		-DLIBCXX_HAS_MUSL_LIBC=$(usex elibc_musl)
+		-DLIBCXX_INCLUDE_BENCHMARKS=OFF
+		-DLIBCXX_INCLUDE_TESTS=$(usex test)
+		-DLIBCXX_INSTALL_MODULES=ON
+		-DLIBCXX_USE_COMPILER_RT=${use_compiler_rt}
+		# this is broken with standalone builds, and also meaningless
+		-DLIBCXXABI_USE_LLVM_UNWINDER=OFF
+	)
+
+	if use test; then
+		mycmakeargs+=(
+			-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+			-DLLVM_LIT_ARGS="$(get_lit_flags)"
+			-DPython3_EXECUTABLE="${PYTHON}"
+		)
+	fi
+	cmake_src_configure
+}
+
+multilib_src_compile() {
+	cmake_src_compile
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		gen_shared_ldscript
+		use static-libs && gen_static_ldscript
+	fi
+}
+
+multilib_src_test() {
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build install-cxx-test-suite-prefix
+	cp "${BUILD_DIR}"/{lib,libcxx/test-suite-install/$(get_libdir)}/libc++_shared.so || die
+	if use static-libs; then
+		cp "${BUILD_DIR}"/{lib,libcxx/test-suite-install/$(get_libdir)}/libc++_static.a || die
+	fi
+	cmake_build check-cxx
+}
+
+multilib_src_install() {
+	cmake_src_install
+	# since we've replaced libc++.{a,so} with ldscripts, now we have to
+	# install the extra symlinks
+	if [[ ${CHOST} != *-darwin* ]] ; then
+		dolib.so lib/libc++_shared.so
+		use static-libs && dolib.a lib/libc++_static.a
+	fi
+}
+
+# Usage: deps
+gen_ldscript() {
+	local output_format
+	output_format=$($(tc-getCC) ${CFLAGS} ${LDFLAGS} -Wl,--verbose 2>&1 | sed -n 's/^OUTPUT_FORMAT("\([^"]*\)",.*/\1/p')
+	[[ -n ${output_format} ]] && output_format="OUTPUT_FORMAT ( ${output_format} )"
+
+	cat <<-END_LDSCRIPT
+/* GNU ld script
+   Include missing dependencies
+*/
+${output_format}
+GROUP ( $@ )
+END_LDSCRIPT
+}
+
+gen_static_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_static}.a || die
+	# Generate libc++.a ldscript for inclusion of its dependencies so that
+	# clang++ -stdlib=libc++ -static works out of the box.
+	local deps=(
+		libc++_static.a
+		$(usex libcxxabi libc++abi.a libsupc++.a)
+	)
+	# On Linux/glibc it does not link without libpthread or libdl. It is
+	# fine on FreeBSD.
+	use elibc_glibc && deps+=( libpthread.a libdl.a )
+
+	gen_ldscript "${deps[*]}" > lib/libc++.a || die
+}
+
+gen_shared_ldscript() {
+	# Move it first.
+	mv lib/libc++{,_shared}.so || die
+	local deps=(
+		libc++_shared.so
+		# libsupc++ doesn't have a shared version
+		$(usex libcxxabi libc++abi.so libsupc++.a)
+	)
+
+	gen_ldscript "${deps[*]}" > lib/libc++.so || die
+}
diff --git a/llvm-runtimes/libcxx/metadata.xml b/llvm-runtimes/libcxx/metadata.xml
new file mode 100644
index 000000000000..c42166cd519a
--- /dev/null
+++ b/llvm-runtimes/libcxx/metadata.xml
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+	<maintainer type="project">
+		<email>llvm@gentoo.org</email>
+		<name>LLVM Project</name>
+	</maintainer>
+	<use>
+		<flag name="clang">Force building using installed clang (rather
+			than the default CC/CXX; required for testing).</flag>
+		<flag name="libcxxabi">Build on top of <pkg>llvm-runtimes/libcxxabi</pkg> instead of gcc's libsupc++ (avoids depending on gcc).</flag>
+	</use>
+	<upstream>
+		<remote-id type="github">llvm/llvm-project</remote-id>
+	</upstream>
+</pkgmetadata>
diff --git a/llvm-runtimes/libcxxabi/libcxxabi-15.0.7.ebuild b/llvm-runtimes/libcxxabi/libcxxabi-15.0.7.ebuild
index a21bc6a0aecd..cf34b0382c22 100644
--- a/llvm-runtimes/libcxxabi/libcxxabi-15.0.7.ebuild
+++ b/llvm-runtimes/libcxxabi/libcxxabi-15.0.7.ebuild
@@ -19,7 +19,7 @@ RESTRICT="!test? ( test )"
 
 # in 15.x, cxxabi.h is moving from libcxx to libcxxabi
 RDEPEND+="
-	!<sys-libs/libcxx-15
+	!<llvm-runtimes/libcxx-15
 "
 DEPEND="
 	${RDEPEND}
diff --git a/llvm-runtimes/libcxxabi/libcxxabi-16.0.6.ebuild b/llvm-runtimes/libcxxabi/libcxxabi-16.0.6.ebuild
index b9dcfb43e585..349898ca2cbd 100644
--- a/llvm-runtimes/libcxxabi/libcxxabi-16.0.6.ebuild
+++ b/llvm-runtimes/libcxxabi/libcxxabi-16.0.6.ebuild
@@ -19,7 +19,7 @@ RESTRICT="!test? ( test )"
 
 # in 15.x, cxxabi.h is moving from libcxx to libcxxabi
 RDEPEND+="
-	!<sys-libs/libcxx-15
+	!<llvm-runtimes/libcxx-15
 "
 DEPEND="
 	${RDEPEND}
diff --git a/llvm-runtimes/libcxxabi/libcxxabi-17.0.6.ebuild b/llvm-runtimes/libcxxabi/libcxxabi-17.0.6.ebuild
index b9dcfb43e585..349898ca2cbd 100644
--- a/llvm-runtimes/libcxxabi/libcxxabi-17.0.6.ebuild
+++ b/llvm-runtimes/libcxxabi/libcxxabi-17.0.6.ebuild
@@ -19,7 +19,7 @@ RESTRICT="!test? ( test )"
 
 # in 15.x, cxxabi.h is moving from libcxx to libcxxabi
 RDEPEND+="
-	!<sys-libs/libcxx-15
+	!<llvm-runtimes/libcxx-15
 "
 DEPEND="
 	${RDEPEND}
diff --git a/llvm-runtimes/libcxxabi/libcxxabi-18.1.8.ebuild b/llvm-runtimes/libcxxabi/libcxxabi-18.1.8.ebuild
index 122f3476e8da..8989f6a96abf 100644
--- a/llvm-runtimes/libcxxabi/libcxxabi-18.1.8.ebuild
+++ b/llvm-runtimes/libcxxabi/libcxxabi-18.1.8.ebuild
@@ -19,7 +19,7 @@ RESTRICT="!test? ( test )"
 
 # in 15.x, cxxabi.h is moving from libcxx to libcxxabi
 RDEPEND+="
-	!<sys-libs/libcxx-15
+	!<llvm-runtimes/libcxx-15
 "
 DEPEND="
 	${RDEPEND}
diff --git a/llvm-runtimes/libcxxabi/libcxxabi-19.1.4.ebuild b/llvm-runtimes/libcxxabi/libcxxabi-19.1.4.ebuild
index 81bed80ba0c9..018c644a3aa5 100644
--- a/llvm-runtimes/libcxxabi/libcxxabi-19.1.4.ebuild
+++ b/llvm-runtimes/libcxxabi/libcxxabi-19.1.4.ebuild
@@ -19,7 +19,7 @@ RESTRICT="!test? ( test )"
 
 # in 15.x, cxxabi.h is moving from libcxx to libcxxabi
 RDEPEND+="
-	!<sys-libs/libcxx-15
+	!<llvm-runtimes/libcxx-15
 "
 DEPEND="
 	${RDEPEND}
diff --git a/llvm-runtimes/libcxxabi/libcxxabi-19.1.5.ebuild b/llvm-runtimes/libcxxabi/libcxxabi-19.1.5.ebuild
index c129f18b4672..891eeea336e9 100644
--- a/llvm-runtimes/libcxxabi/libcxxabi-19.1.5.ebuild
+++ b/llvm-runtimes/libcxxabi/libcxxabi-19.1.5.ebuild
@@ -19,7 +19,7 @@ RESTRICT="!test? ( test )"
 
 # in 15.x, cxxabi.h is moving from libcxx to libcxxabi
 RDEPEND+="
-	!<sys-libs/libcxx-15
+	!<llvm-runtimes/libcxx-15
 "
 DEPEND="
 	${RDEPEND}
diff --git a/llvm-runtimes/libcxxabi/libcxxabi-20.0.0.9999.ebuild b/llvm-runtimes/libcxxabi/libcxxabi-20.0.0.9999.ebuild
index 13b5d3b6c275..55e6c9c566f2 100644
--- a/llvm-runtimes/libcxxabi/libcxxabi-20.0.0.9999.ebuild
+++ b/llvm-runtimes/libcxxabi/libcxxabi-20.0.0.9999.ebuild
@@ -18,7 +18,7 @@ RESTRICT="!test? ( test )"
 
 # in 15.x, cxxabi.h is moving from libcxx to libcxxabi
 RDEPEND+="
-	!<sys-libs/libcxx-15
+	!<llvm-runtimes/libcxx-15
 "
 DEPEND="
 	${RDEPEND}
diff --git a/llvm-runtimes/libcxxabi/libcxxabi-20.0.0_pre20241207.ebuild b/llvm-runtimes/libcxxabi/libcxxabi-20.0.0_pre20241207.ebuild
index 13b5d3b6c275..55e6c9c566f2 100644
--- a/llvm-runtimes/libcxxabi/libcxxabi-20.0.0_pre20241207.ebuild
+++ b/llvm-runtimes/libcxxabi/libcxxabi-20.0.0_pre20241207.ebuild
@@ -18,7 +18,7 @@ RESTRICT="!test? ( test )"
 
 # in 15.x, cxxabi.h is moving from libcxx to libcxxabi
 RDEPEND+="
-	!<sys-libs/libcxx-15
+	!<llvm-runtimes/libcxx-15
 "
 DEPEND="
 	${RDEPEND}