diff --git a/sys-devel/llvm/Manifest b/sys-devel/llvm/Manifest
index 093060ae4ff68..92306c4e98ee9 100644
--- a/sys-devel/llvm/Manifest
+++ b/sys-devel/llvm/Manifest
@@ -23,4 +23,5 @@ DIST llvm-project-18.1.8.src.tar.xz.sig 566 BLAKE2B 6ab0efc5b38d4483f4e32e8b8577
 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-19ddafafdf131aed40abbdaf5af1fb7b59c1e8ac.tar.gz 223281446 BLAKE2B 68f8e9bbae78938f424f566bf60db489e5c8afc4ae307cce11adb4b9b6dd48f1c54f1ef69b81051a702cb213012a0e5e03f602a29b11488d79a6bc5e49aa3402 SHA512 6355dd6f8992c6d14f20ce1976fc588f198a42c3c7eaa6c463e63b5110759decdebb80ea357c5e29620d8c33b6da752cbb8d2853159dc0e887f6c3d733c80eca
+DIST llvm-project-a348f223cab54b21a7b1c38dec7bc6aa2f81c949.tar.gz 223630067 BLAKE2B 3c2121a8d13e3a84a9ee98d17c58e5fd5a31d5870ac21c633c78c49b4af0c401310f7e91f64ff3b7cf7f6e8d205c730458b8b1101b1255f422659974d48e2ecb SHA512 33cc09a904e4fe0d529611a1d71d764e6d49f014cea903aadc0755d0420f65cfc763fdcfd4bb9a96adad79ce1c4475d8c005dcac37c4fe130a1fb3665172f1db
 DIST llvm-project-a6385a3fc8a88f092d07672210a1e773481c2919.tar.gz 222866102 BLAKE2B 9346275b18dcd7eedb699ed3494c027f597f68ceb8ff902fbff9f805a2c423d4fb86619974b3bb6fea30c5fe948e3793fb5c499f9e206b61794e13908d830327 SHA512 ac507feeaba787c6df1ece65e03d065c4f8fbabef686b583f671745e09c9a585be8c9359aeb3aa77815711a2ff9621c1b36a4d24cfe9f8d04e3288b53d7c9c69
diff --git a/sys-devel/llvm/llvm-20.0.0_pre20241130.ebuild b/sys-devel/llvm/llvm-20.0.0_pre20241130.ebuild
new file mode 100644
index 0000000000000..d01575f39051f
--- /dev/null
+++ b/sys-devel/llvm/llvm-20.0.0_pre20241130.ebuild
@@ -0,0 +1,554 @@
+# 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 flag-o-matic llvm.org multilib-minimal pax-utils python-any-r1
+inherit toolchain-funcs
+
+DESCRIPTION="Low Level Virtual Machine"
+HOMEPAGE="https://llvm.org/"
+
+# Additional licenses:
+# 1. OpenBSD regex: Henry Spencer's license ('rc' in Gentoo) + BSD.
+# 2. xxhash: BSD.
+# 3. MD5 code: public-domain.
+# 4. ConvertUTF.h: TODO.
+
+LICENSE="Apache-2.0-with-LLVM-exceptions UoI-NCSA BSD public-domain rc"
+SLOT="${LLVM_MAJOR}/${LLVM_SOABI}"
+IUSE="
+	+binutils-plugin +debug debuginfod doc exegesis libedit +libffi
+	test xml z3 zstd
+"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	sys-libs/zlib:0=[${MULTILIB_USEDEP}]
+	debuginfod? (
+		net-misc/curl:=
+		dev-cpp/cpp-httplib:=
+	)
+	exegesis? ( dev-libs/libpfm:= )
+	libedit? ( dev-libs/libedit:0=[${MULTILIB_USEDEP}] )
+	libffi? ( >=dev-libs/libffi-3.0.13-r1:0=[${MULTILIB_USEDEP}] )
+	xml? ( dev-libs/libxml2:2=[${MULTILIB_USEDEP}] )
+	z3? ( >=sci-mathematics/z3-4.7.1:0=[${MULTILIB_USEDEP}] )
+	zstd? ( app-arch/zstd:=[${MULTILIB_USEDEP}] )
+"
+DEPEND="
+	${RDEPEND}
+	binutils-plugin? ( sys-libs/binutils-libs )
+"
+BDEPEND="
+	${PYTHON_DEPS}
+	dev-lang/perl
+	sys-devel/gnuconfig
+	kernel_Darwin? (
+		<sys-libs/libcxx-${LLVM_VERSION}.9999
+	)
+	libffi? ( virtual/pkgconfig )
+"
+# There are no file collisions between these versions but having :0
+# installed means llvm-config there will take precedence.
+RDEPEND="
+	${RDEPEND}
+	!sys-devel/llvm:0
+"
+PDEPEND="
+	sys-devel/llvm-common
+	sys-devel/llvm-toolchain-symlinks:${LLVM_MAJOR}
+	binutils-plugin? ( >=sys-devel/llvmgold-${LLVM_MAJOR} )
+"
+
+LLVM_COMPONENTS=( llvm cmake third-party )
+LLVM_MANPAGES=1
+LLVM_USE_TARGETS=provide
+llvm.org_set_globals
+
+[[ -n ${LLVM_MANPAGE_DIST} ]] && BDEPEND+=" doc? ( "
+BDEPEND+="
+	$(python_gen_any_dep '
+		dev-python/myst-parser[${PYTHON_USEDEP}]
+		dev-python/sphinx[${PYTHON_USEDEP}]
+	')
+"
+[[ -n ${LLVM_MANPAGE_DIST} ]] && BDEPEND+=" ) "
+
+python_check_deps() {
+	llvm_are_manpages_built || return 0
+
+	python_has_version -b "dev-python/myst-parser[${PYTHON_USEDEP}]" &&
+	python_has_version -b "dev-python/sphinx[${PYTHON_USEDEP}]"
+}
+
+check_uptodate() {
+	local prod_targets=(
+		$(sed -n -e '/set(LLVM_ALL_TARGETS/,/)/p' CMakeLists.txt \
+			| tail -n +2 | head -n -1)
+	)
+	local all_targets=(
+		lib/Target/*/
+	)
+	all_targets=( "${all_targets[@]#lib/Target/}" )
+	all_targets=( "${all_targets[@]%/}" )
+
+	local exp_targets=() i
+	for i in "${all_targets[@]}"; do
+		has "${i}" "${prod_targets[@]}" || exp_targets+=( "${i}" )
+	done
+
+	local outdated
+	if [[ ${exp_targets[*]} != ${ALL_LLVM_EXPERIMENTAL_TARGETS[*]} ]]; then
+		eerror "ALL_LLVM_EXPERIMENTAL_TARGETS are outdated!"
+		eerror "    Have: ${ALL_LLVM_EXPERIMENTAL_TARGETS[*]}"
+		eerror "Expected: ${exp_targets[*]}"
+		eerror
+		outdated=1
+	fi
+
+	if [[ ${prod_targets[*]} != ${ALL_LLVM_PRODUCTION_TARGETS[*]} ]]; then
+		eerror "ALL_LLVM_PRODUCTION_TARGETS are outdated!"
+		eerror "    Have: ${ALL_LLVM_PRODUCTION_TARGETS[*]}"
+		eerror "Expected: ${prod_targets[*]}"
+		outdated=1
+	fi
+
+	[[ ${outdated} ]] && die "Update ALL_LLVM*_TARGETS"
+}
+
+check_distribution_components() {
+	if [[ ${CMAKE_MAKEFILE_GENERATOR} == ninja ]]; then
+		local all_targets=() my_targets=() l
+		cd "${BUILD_DIR}" || die
+
+		while read -r l; do
+			if [[ ${l} == install-*-stripped:* ]]; then
+				l=${l#install-}
+				l=${l%%-stripped*}
+
+				case ${l} in
+					# shared libs
+					LLVM|LLVMgold)
+						;;
+					# TableGen lib + deps
+					LLVMDemangle|LLVMSupport|LLVMTableGen)
+						;;
+					# used by lldb
+					LLVMDebuginfod)
+						;;
+					# testing libraries
+					LLVMTestingAnnotations|LLVMTestingSupport)
+						;;
+					# static libs
+					LLVM*)
+						continue
+						;;
+					# meta-targets
+					distribution|llvm-libraries)
+						continue
+						;;
+					# used only w/ USE=doc
+					docs-llvm-html)
+						use doc || continue
+						;;
+					# used only w/ USE=debuginfd
+					llvm-debuginfod)
+						use debuginfod || continue
+						;;
+				esac
+
+				all_targets+=( "${l}" )
+			fi
+		done < <(${NINJA} -t targets all)
+
+		while read -r l; do
+			my_targets+=( "${l}" )
+		done < <(get_distribution_components $"\n")
+
+		local add=() remove=()
+		for l in "${all_targets[@]}"; do
+			if ! has "${l}" "${my_targets[@]}"; then
+				add+=( "${l}" )
+			fi
+		done
+		for l in "${my_targets[@]}"; do
+			if ! has "${l}" "${all_targets[@]}"; then
+				remove+=( "${l}" )
+			fi
+		done
+
+		if [[ ${#add[@]} -gt 0 || ${#remove[@]} -gt 0 ]]; then
+			eerror "get_distribution_components() is outdated!"
+			eerror "   Add: ${add[*]}"
+			eerror "Remove: ${remove[*]}"
+			die "Update get_distribution_components()!"
+		fi
+		cd - >/dev/null || die
+	fi
+}
+
+src_prepare() {
+	# disable use of SDK on OSX, bug #568758
+	sed -i -e 's/xcrun/false/' utils/lit/lit/util.py || die
+
+	# Update config.guess to support more systems
+	cp "${BROOT}/usr/share/gnuconfig/config.guess" cmake/ || die
+
+	# Verify that the ebuild is up-to-date
+	check_uptodate
+
+	llvm.org_src_prepare
+}
+
+get_distribution_components() {
+	local sep=${1-;}
+
+	local out=(
+		# shared libs
+		LLVM
+		LTO
+		Remarks
+
+		# tools
+		llvm-config
+
+		# common stuff
+		cmake-exports
+		llvm-headers
+
+		# libraries needed for clang-tblgen
+		LLVMDemangle
+		LLVMSupport
+		LLVMTableGen
+
+		# testing libraries
+		llvm_gtest
+		llvm_gtest_main
+		LLVMTestingAnnotations
+		LLVMTestingSupport
+	)
+
+	if multilib_is_native_abi; then
+		out+=(
+			# library used by lldb
+			LLVMDebuginfod
+
+			# utilities
+			llvm-tblgen
+			FileCheck
+			llvm-PerfectShuffle
+			count
+			not
+			yaml-bench
+			UnicodeNameMappingGenerator
+
+			# tools
+			bugpoint
+			dsymutil
+			llc
+			lli
+			lli-child-target
+			llvm-addr2line
+			llvm-ar
+			llvm-as
+			llvm-bcanalyzer
+			llvm-bitcode-strip
+			llvm-c-test
+			llvm-cat
+			llvm-cfi-verify
+			llvm-cgdata
+			llvm-config
+			llvm-cov
+			llvm-ctxprof-util
+			llvm-cvtres
+			llvm-cxxdump
+			llvm-cxxfilt
+			llvm-cxxmap
+			llvm-debuginfo-analyzer
+			llvm-debuginfod-find
+			llvm-diff
+			llvm-dis
+			llvm-dlltool
+			llvm-dwarfdump
+			llvm-dwarfutil
+			llvm-dwp
+			llvm-exegesis
+			llvm-extract
+			llvm-gsymutil
+			llvm-ifs
+			llvm-install-name-tool
+			llvm-jitlink
+			llvm-jitlink-executor
+			llvm-lib
+			llvm-libtool-darwin
+			llvm-link
+			llvm-lipo
+			llvm-lto
+			llvm-lto2
+			llvm-mc
+			llvm-mca
+			llvm-ml
+			llvm-modextract
+			llvm-mt
+			llvm-nm
+			llvm-objcopy
+			llvm-objdump
+			llvm-opt-report
+			llvm-otool
+			llvm-pdbutil
+			llvm-profdata
+			llvm-profgen
+			llvm-ranlib
+			llvm-rc
+			llvm-readelf
+			llvm-readobj
+			llvm-readtapi
+			llvm-reduce
+			llvm-remarkutil
+			llvm-rtdyld
+			llvm-sim
+			llvm-size
+			llvm-split
+			llvm-stress
+			llvm-strings
+			llvm-strip
+			llvm-symbolizer
+			llvm-tli-checker
+			llvm-undname
+			llvm-windres
+			llvm-xray
+			obj2yaml
+			opt
+			reduce-chunk-list
+			sancov
+			sanstats
+			split-file
+			verify-uselistorder
+			yaml2obj
+
+			# python modules
+			opt-viewer
+		)
+
+		if llvm_are_manpages_built; then
+			out+=(
+				# manpages
+				docs-dsymutil-man
+				docs-llvm-dwarfdump-man
+				docs-llvm-man
+			)
+		fi
+		use doc && out+=(
+			docs-llvm-html
+		)
+
+		use binutils-plugin && out+=(
+			LLVMgold
+		)
+		use debuginfod && out+=(
+			llvm-debuginfod
+		)
+	fi
+
+	printf "%s${sep}" "${out[@]}"
+}
+
+multilib_src_configure() {
+	if use ppc && tc-is-gcc && [[ $(gcc-major-version) -lt 14 ]]; then
+		# Workaround for bug #880677
+		append-flags $(test-flags-CXX -fno-ipa-sra -fno-ipa-modref -fno-ipa-icf)
+	fi
+
+	# ODR violations (bug #917536, bug #926529). Just do it for GCC for now
+	# to avoid people grumbling. GCC is, anecdotally, more likely to miscompile
+	# LLVM with LTO anyway (which is not necessarily its fault).
+	tc-is-gcc && filter-lto
+
+	local ffi_cflags ffi_ldflags
+	if use libffi; then
+		ffi_cflags=$($(tc-getPKG_CONFIG) --cflags-only-I libffi)
+		ffi_ldflags=$($(tc-getPKG_CONFIG) --libs-only-L libffi)
+	fi
+
+	local libdir=$(get_libdir)
+	local mycmakeargs=(
+		# disable appending VCS revision to the version to improve
+		# direct cache hit ratio
+		-DLLVM_APPEND_VC_REV=OFF
+		-DCMAKE_INSTALL_PREFIX="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}"
+		-DLLVM_LIBDIR_SUFFIX=${libdir#lib}
+
+		-DBUILD_SHARED_LIBS=OFF
+		-DLLVM_BUILD_LLVM_DYLIB=ON
+		-DLLVM_LINK_LLVM_DYLIB=ON
+		-DLLVM_DISTRIBUTION_COMPONENTS=$(get_distribution_components)
+
+		# cheap hack: LLVM combines both anyway, and the only difference
+		# is that the former list is explicitly verified at cmake time
+		-DLLVM_TARGETS_TO_BUILD=""
+		-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD="${LLVM_TARGETS// /;}"
+		-DLLVM_INCLUDE_BENCHMARKS=OFF
+		-DLLVM_INCLUDE_TESTS=ON
+		-DLLVM_BUILD_TESTS=$(usex test)
+		-DLLVM_INSTALL_GTEST=ON
+
+		-DLLVM_ENABLE_FFI=$(usex libffi)
+		-DLLVM_ENABLE_LIBEDIT=$(usex libedit)
+		-DLLVM_ENABLE_LIBXML2=$(usex xml)
+		-DLLVM_ENABLE_ASSERTIONS=$(usex debug)
+		-DLLVM_ENABLE_LIBPFM=$(usex exegesis)
+		-DLLVM_ENABLE_EH=ON
+		-DLLVM_ENABLE_RTTI=ON
+		-DLLVM_ENABLE_Z3_SOLVER=$(usex z3)
+		-DLLVM_ENABLE_ZLIB=FORCE_ON
+		-DLLVM_ENABLE_ZSTD=$(usex zstd FORCE_ON OFF)
+		-DLLVM_ENABLE_CURL=$(usex debuginfod)
+		-DLLVM_ENABLE_HTTPLIB=$(usex debuginfod)
+
+		-DLLVM_HOST_TRIPLE="${CHOST}"
+
+		-DFFI_INCLUDE_DIR="${ffi_cflags#-I}"
+		-DFFI_LIBRARY_DIR="${ffi_ldflags#-L}"
+
+		-DPython3_EXECUTABLE="${PYTHON}"
+
+		# disable OCaml bindings (now in dev-ml/llvm-ocaml)
+		-DOCAMLFIND=NO
+	)
+
+	local suffix=
+	if [[ -n ${EGIT_VERSION} && ${EGIT_BRANCH} != release/* ]]; then
+		# the ABI of the main branch is not stable, so let's include
+		# the commit id in the SOVERSION to contain the breakage
+		suffix+="git${EGIT_VERSION::8}"
+	fi
+	if [[ $(tc-get-cxx-stdlib) == libc++ ]]; then
+		# Smart hack: alter version suffix -> SOVERSION when linking
+		# against libc++. This way we won't end up mixing LLVM libc++
+		# libraries with libstdc++ clang, and the other way around.
+		suffix+="+libcxx"
+		mycmakeargs+=(
+			-DLLVM_ENABLE_LIBCXX=ON
+		)
+	fi
+	mycmakeargs+=(
+		-DLLVM_VERSION_SUFFIX="${suffix}"
+	)
+
+	use test && mycmakeargs+=(
+		-DLLVM_LIT_ARGS="$(get_lit_flags)"
+	)
+
+	if multilib_is_native_abi; then
+		local build_docs=OFF
+		if llvm_are_manpages_built; then
+			build_docs=ON
+			mycmakeargs+=(
+				-DCMAKE_INSTALL_MANDIR="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/share/man"
+				-DLLVM_INSTALL_SPHINX_HTML_DIR="${EPREFIX}/usr/share/doc/${PF}/html"
+				-DSPHINX_WARNINGS_AS_ERRORS=OFF
+			)
+		fi
+
+		mycmakeargs+=(
+			-DLLVM_BUILD_DOCS=${build_docs}
+			-DLLVM_ENABLE_OCAMLDOC=OFF
+			-DLLVM_ENABLE_SPHINX=${build_docs}
+			-DLLVM_ENABLE_DOXYGEN=OFF
+			-DLLVM_INSTALL_UTILS=ON
+		)
+		use binutils-plugin && mycmakeargs+=(
+			-DLLVM_BINUTILS_INCDIR="${EPREFIX}"/usr/include
+		)
+	fi
+
+	use kernel_Darwin && mycmakeargs+=(
+		# Use our libtool instead of looking it up with xcrun
+		-DCMAKE_LIBTOOL="${EPREFIX}/usr/bin/${CHOST}-libtool"
+	)
+
+	# LLVM can have very high memory consumption while linking,
+	# exhausting the limit on 32-bit linker executable
+	use x86 && local -x LDFLAGS="${LDFLAGS} -Wl,--no-keep-memory"
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+	cmake_src_configure
+
+	grep -q -E "^CMAKE_PROJECT_VERSION_MAJOR(:.*)?=${LLVM_MAJOR}$" \
+			CMakeCache.txt ||
+		die "Incorrect version, did you update _LLVM_MAIN_MAJOR?"
+	multilib_is_native_abi && check_distribution_components
+}
+
+multilib_src_compile() {
+	tc-env_build cmake_build distribution
+
+	pax-mark m "${BUILD_DIR}"/bin/llvm-rtdyld
+	pax-mark m "${BUILD_DIR}"/bin/lli
+	pax-mark m "${BUILD_DIR}"/bin/lli-child-target
+
+	if use test; then
+		pax-mark m "${BUILD_DIR}"/unittests/ExecutionEngine/Orc/OrcJITTests
+		pax-mark m "${BUILD_DIR}"/unittests/ExecutionEngine/MCJIT/MCJITTests
+		pax-mark m "${BUILD_DIR}"/unittests/Support/SupportTests
+	fi
+}
+
+multilib_src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check
+}
+
+src_install() {
+	local MULTILIB_CHOST_TOOLS=(
+		/usr/lib/llvm/${LLVM_MAJOR}/bin/llvm-config
+	)
+
+	local MULTILIB_WRAPPED_HEADERS=(
+		/usr/include/llvm/Config/llvm-config.h
+	)
+
+	local LLVM_LDPATHS=()
+	multilib-minimal_src_install
+
+	# move wrapped headers back
+	mv "${ED}"/usr/include "${ED}"/usr/lib/llvm/${LLVM_MAJOR}/include || die
+}
+
+multilib_src_install() {
+	DESTDIR=${D} cmake_build install-distribution
+
+	# move headers to /usr/include for wrapping
+	rm -rf "${ED}"/usr/include || die
+	mv "${ED}"/usr/lib/llvm/${LLVM_MAJOR}/include "${ED}"/usr/include || die
+
+	LLVM_LDPATHS+=( "${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/$(get_libdir)" )
+}
+
+multilib_src_install_all() {
+	local revord=$(( 9999 - ${LLVM_MAJOR} ))
+	newenvd - "60llvm-${revord}" <<-_EOF_
+		PATH="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/bin"
+		# we need to duplicate it in ROOTPATH for Portage to respect...
+		ROOTPATH="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/bin"
+		MANPATH="${EPREFIX}/usr/lib/llvm/${LLVM_MAJOR}/share/man"
+		LDPATH="$( IFS=:; echo "${LLVM_LDPATHS[*]}" )"
+	_EOF_
+
+	docompress "/usr/lib/llvm/${LLVM_MAJOR}/share/man"
+	llvm_install_manpages
+}
+
+pkg_postinst() {
+	elog "You can find additional opt-viewer utility scripts in:"
+	elog "  ${EROOT}/usr/lib/llvm/${LLVM_MAJOR}/share/opt-viewer"
+	elog "To use these scripts, you will need Python along with the following"
+	elog "packages:"
+	elog "  dev-python/pygments (for opt-viewer)"
+	elog "  dev-python/pyyaml (for all of them)"
+}