diff --git a/llvm-runtimes/flang-rt/Manifest b/llvm-runtimes/flang-rt/Manifest
new file mode 100644
index 0000000000000..077ac2c8fe68d
--- /dev/null
+++ b/llvm-runtimes/flang-rt/Manifest
@@ -0,0 +1 @@
+DIST llvm-project-581599096e8a1a89ccd3e053a1209c69a9079083.tar.gz 227830555 BLAKE2B 28a04dd5ce96716d389fe049c4b877f55d6e5cad5c77d8867dd7e3a448213ef413e4f4d7d5f77b0702b26a8eb25f53e08d90e2a5a97eaa3f89245531d9f6626d SHA512 d775aea9bf71d60673e966a689ff6b933afecab2c133a1f64a158551ba9db049221148eab5087bab0ce0ff917456b85fb4ea4d7284886326f54617d167a385a5
diff --git a/llvm-runtimes/flang-rt/flang-rt-21.0.0.9999.ebuild b/llvm-runtimes/flang-rt/flang-rt-21.0.0.9999.ebuild
new file mode 100644
index 0000000000000..30245857a84e0
--- /dev/null
+++ b/llvm-runtimes/flang-rt/flang-rt-21.0.0.9999.ebuild
@@ -0,0 +1,72 @@
+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit cmake flag-o-matic llvm.org
+
+DESCRIPTION="LLVM's Fortran runtime"
+HOMEPAGE="https://flang.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions"
+SLOT="${LLVM_MAJOR}"
+IUSE="+debug test"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	!<llvm-core/flang-21.0.0_pre20250221-r1
+"
+BDEPEND="
+	llvm-core/llvm:${LLVM_MAJOR}
+	llvm-core/flang
+	test? (
+		dev-python/lit
+	)
+"
+
+LLVM_COMPONENTS=(
+	runtimes flang-rt cmake flang llvm/{cmake,utils/llvm-lit}
+)
+llvm.org_set_globals
+
+src_configure() {
+	# the code is not portable
+	local -x FC=flang F77=flang
+	strip-unsupported-flags
+
+	local mycmakeargs=(
+		# we may not have a runtime yet
+		-DCMAKE_Fortran_COMPILER_WORKS=TRUE
+
+		-DLLVM_ENABLE_RUNTIMES="flang-rt"
+		# this package forces NO_DEFAULT_PATHS
+		-DLLVM_BINARY_DIR="${ESYSROOT}/usr/lib/llvm/${LLVM_MAJOR}"
+
+		-DFLANG_RT_INCLUDE_TESTS=$(usex test)
+	)
+	use test && mycmakeargs+=(
+		-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+		-DLLVM_LIT_ARGS="$(get_lit_flags)"
+	)
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+	cmake_src_configure
+}
+
+src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-flang-rt
+}
+
+src_install() {
+	cmake_src_install
+
+	# in standalone build, the library is installed to (incorrect) resource dir
+	# but the driver only looks for it in lib (sigh)
+	# https://github.com/llvm/llvm-project/issues/127538
+	mkdir -p "${ED}/usr/lib/llvm/${LLVM_MAJOR}" || die
+	mv "${ED}/usr/$(get_libdir)/clang/${LLVM_MAJOR}/lib"/* \
+		"${ED}/usr/lib/llvm/${LLVM_MAJOR}/lib" || die
+}
diff --git a/llvm-runtimes/flang-rt/flang-rt-21.0.0_pre20250221.ebuild b/llvm-runtimes/flang-rt/flang-rt-21.0.0_pre20250221.ebuild
new file mode 100644
index 0000000000000..30245857a84e0
--- /dev/null
+++ b/llvm-runtimes/flang-rt/flang-rt-21.0.0_pre20250221.ebuild
@@ -0,0 +1,72 @@
+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit cmake flag-o-matic llvm.org
+
+DESCRIPTION="LLVM's Fortran runtime"
+HOMEPAGE="https://flang.llvm.org/"
+
+LICENSE="Apache-2.0-with-LLVM-exceptions"
+SLOT="${LLVM_MAJOR}"
+IUSE="+debug test"
+RESTRICT="!test? ( test )"
+
+RDEPEND="
+	!<llvm-core/flang-21.0.0_pre20250221-r1
+"
+BDEPEND="
+	llvm-core/llvm:${LLVM_MAJOR}
+	llvm-core/flang
+	test? (
+		dev-python/lit
+	)
+"
+
+LLVM_COMPONENTS=(
+	runtimes flang-rt cmake flang llvm/{cmake,utils/llvm-lit}
+)
+llvm.org_set_globals
+
+src_configure() {
+	# the code is not portable
+	local -x FC=flang F77=flang
+	strip-unsupported-flags
+
+	local mycmakeargs=(
+		# we may not have a runtime yet
+		-DCMAKE_Fortran_COMPILER_WORKS=TRUE
+
+		-DLLVM_ENABLE_RUNTIMES="flang-rt"
+		# this package forces NO_DEFAULT_PATHS
+		-DLLVM_BINARY_DIR="${ESYSROOT}/usr/lib/llvm/${LLVM_MAJOR}"
+
+		-DFLANG_RT_INCLUDE_TESTS=$(usex test)
+	)
+	use test && mycmakeargs+=(
+		-DLLVM_EXTERNAL_LIT="${EPREFIX}/usr/bin/lit"
+		-DLLVM_LIT_ARGS="$(get_lit_flags)"
+	)
+
+	# LLVM_ENABLE_ASSERTIONS=NO does not guarantee this for us, #614844
+	use debug || local -x CPPFLAGS="${CPPFLAGS} -DNDEBUG"
+	cmake_src_configure
+}
+
+src_test() {
+	# respect TMPDIR!
+	local -x LIT_PRESERVES_TMP=1
+	cmake_build check-flang-rt
+}
+
+src_install() {
+	cmake_src_install
+
+	# in standalone build, the library is installed to (incorrect) resource dir
+	# but the driver only looks for it in lib (sigh)
+	# https://github.com/llvm/llvm-project/issues/127538
+	mkdir -p "${ED}/usr/lib/llvm/${LLVM_MAJOR}" || die
+	mv "${ED}/usr/$(get_libdir)/clang/${LLVM_MAJOR}/lib"/* \
+		"${ED}/usr/lib/llvm/${LLVM_MAJOR}/lib" || die
+}
diff --git a/llvm-runtimes/flang-rt/metadata.xml b/llvm-runtimes/flang-rt/metadata.xml
new file mode 100644
index 0000000000000..072910296ca3d
--- /dev/null
+++ b/llvm-runtimes/flang-rt/metadata.xml
@@ -0,0 +1,10 @@
+<?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>
+	</maintainer>
+	<upstream>
+		<remote-id type="github">llvm/llvm-project</remote-id>
+	</upstream>
+</pkgmetadata>