--- sys-libs/libcxx/libcxx-9999.ebuild.orig	2015-02-07 22:12:53.000000000 +0100
+++ sys-libs/libcxx/libcxx-9999.ebuild.orig	2015-02-08 00:26:14.000000000 +0100
@@ -13,7 +13,9 @@ 
 DESCRIPTION="New implementation of the C++ standard library, targeting C++11"
 HOMEPAGE="http://libcxx.llvm.org/"
 if [ "${PV%9999}" = "${PV}" ] ; then
-	SRC_URI="mirror://gentoo/${P}.tar.xz"
+	SRC_URI="mirror://gentoo/${P}.src.tar.xz
+		http://llvm.org/releases/${PV}/${P}.src.tar.xz"
+	S="${WORKDIR}"/"${P}".src
 else
 	SRC_URI=""
 fi
@@ -21,14 +23,17 @@ 
 LICENSE="|| ( UoI-NCSA MIT )"
 SLOT="0"
 if [ "${PV%9999}" = "${PV}" ] ; then
-	KEYWORDS="~amd64 ~mips ~x86 ~amd64-fbsd ~x86-fbsd ~amd64-linux ~x86-linux"
+	KEYWORDS="~amd64 ~mips ~x86 ~amd64-fbsd ~x86-fbsd ~amd64-linux ~x86-linux ~x64-macos ~x86-macos"
 else
 	KEYWORDS=""
 fi
-IUSE="elibc_glibc +libcxxrt static-libs test"
+IUSE="elibc_glibc libsupc static-libs test"
 
-RDEPEND="libcxxrt? ( >=sys-libs/libcxxrt-0.0_p20130725[static-libs?,${MULTILIB_USEDEP}] )
-	!libcxxrt? ( >=sys-devel/gcc-4.7[cxx] )"
+REQUIRED_USE="kernel_Darwin? ( !libsupc !static-libs )"
+RDEPEND="!kernel_Darwin? (
+		!libsupc? ( >=sys-libs/libcxxrt-0.0_p20130725[static-libs?,${MULTILIB_USEDEP}] )
+		libsupc? ( >=sys-devel/gcc-4.7[cxx] ) )
+	kernel_Darwin? ( sys-libs/libcxx-headers sys-libs/libcxxabi sys-devel/clang )"
 DEPEND="${RDEPEND}
 	test? ( sys-devel/clang )
 	app-arch/xz-utils"
@@ -36,8 +41,19 @@ 
 DOCS=( CREDITS.TXT )
 
 pkg_setup() {
-	if ! use libcxxrt ; then
-		ewarn "You have disabled USE=libcxxrt. This will build ${PN} against"
+	if [[ ${CHOST} == *darwin* ]] ; then
+		MY_CC=$(tc-getCC)
+		MY_CXX=$(tc-getCXX)
+		if [[ ${MY_CC} != *clang* || ${MY_CXX} != *clang++* ]] ; then
+			eerror "${PN} needs to be built with clang++. Please do not override"
+			eerror "CC ($MY_CC) and CXX ($MY_CXX)"
+			eerror "or point them at clang and eerror clang++ respectively."
+			die
+		fi
+		return
+	fi
+	if use libsupc ; then
+		ewarn "You have enabled USE=libsupc. This will build ${PN} against"
 		ewarn "libsupc++. Please note that this is not well supported."
 		ewarn "In particular, static linking will not work."
 	fi
@@ -50,12 +66,51 @@ 
 
 src_prepare() {
 	cp -f "${FILESDIR}/Makefile" lib/ || die
+
+	if [[ ${CHOST} == *darwin* ]] ; then
+		epatch "${FILESDIR}"/${PN}-3.5.1-olddarwin.patch
+
+		[[ "${CHOST##*-darwin}" -le 10 ]] && \
+			epatch "${FILESDIR}"/${PN}-3.5.1-cmath-conv.patch
+
+		# libc++abi needs stack unwinding functions provided by libSystem on
+		# Mac OS X >= 10.6. On < 10.6 they're in libgcc_s. So force link
+		# against that. Additionally, the crt1.o provided by our gcc-apple
+		# toolchain isn't universal. Since that's needed for linking any
+		# program on OS X < 10.7, universal support is effectively broken on
+		# those older OS Xes even if clang and libc++{,abi} were to support it.
+		# So we can just disable universal compilation.
+		gcc_s=gcc_s.1
+		[[ "${CHOST##*-darwin}" -eq 9 ]] && gcc_s=gcc_s.10.5
+		[[ "${CHOST##*-darwin}" -eq 8 ]] && gcc_s=gcc_s.10.4
+		[[ "${CHOST##*-darwin}" -le 9 ]]  && \
+			sed -i -e "s,/usr/lib/libSystem.B.dylib,-lSystem -l${gcc_s},g" \
+				-e "s,-arch i386 -arch x86_64,,g" \
+				lib/buildit
+
+		if [[ "${CHOST##*-darwin}" -le 8 ]] ; then
+			epatch "${FILESDIR}"/${PN}-3.5.1-availability.patch
+			epatch "${FILESDIR}"/${PN}-3.5.1-eprintf.patch
+		fi
+
+		# fix library install names
+		sed -i \
+			-e "s,/usr/lib/libc++abi\.dylib,${EPREFIX}/usr/lib/libc++abi.dylib,g" \
+			-e "s,/usr/lib/libc++\.1\.dylib,${EPREFIX}/usr/lib/libc++.1.dylib,g" \
+			lib/buildit
+	fi
+
 	multilib_copy_sources
 }
 
 src_configure() {
+	tc-export AR CC CXX
+
+	# on Darwin we're all set
+	[[ ${CHOST} == *darwin* ]] && return
+
 	export LIBS="-lpthread -lrt -lc -lgcc_s"
-	if use libcxxrt ; then
+	if ! use libsupc ; then
 		append-cppflags -DLIBCXXRT "-I${EPREFIX}/usr/include/libcxxrt/"
 		LIBS="-lcxxrt ${LIBS}"
 		cp "${EPREFIX}/usr/include/libcxxrt/"*.h "${S}/include"
@@ -80,13 +135,16 @@ 
 		done
 	fi
 
-	tc-export AR CC CXX
-
 	append-ldflags "-Wl,-z,defs" # make sure we are not underlinked
 }
 
 multilib_src_compile() {
 	cd "${BUILD_DIR}/lib" || die
+	if [[ ${CHOST} == *darwin* ]] ; then
+		TRIPLE=-apple- ./buildit || die
+		return
+	fi
+
 	emake shared
 	use static-libs && emake static
 }
@@ -98,7 +156,7 @@ 
 		CC="clang++ $(get_abi_CFLAGS) ${CXXFLAGS}" \
 		HEADER_INCLUDE="-I${BUILD_DIR}/include" \
 		SOURCE_LIB="-L${BUILD_DIR}/lib" \
-		LIBS="-lm $(usex libcxxrt -lcxxrt "")" \
+		LIBS="-lm $(usex libsupc "" -lcxxrt)" \
 		./testit || die
 	# TODO: fix link against libsupc++
 }
@@ -119,7 +177,7 @@ 
 }
 
 gen_static_ldscript() {
-	if use libcxxrt ; then
+	if ! use libsupc ; then
 		# Move it first.
 		mv "${ED}/usr/$(get_libdir)/libc++.a" "${ED}/usr/$(get_libdir)/libc++_static.a" || die
 
@@ -136,7 +194,7 @@ 
 }
 
 gen_shared_ldscript() {
-	if use libcxxrt ; then
+	if ! use libsupc ; then
 		mv "${ED}/usr/$(get_libdir)/libc++.so" "${ED}/usr/$(get_libdir)/libc++_shared.so" || die
 		local deps="${EPREFIX}/usr/$(get_libdir)/libc++_shared.so ${EPREFIX}/usr/$(get_libdir)/libcxxrt.so"
 		gen_ldscript "${deps}" > "${ED}/usr/$(get_libdir)/libc++.so"
@@ -146,6 +204,11 @@ 
 
 multilib_src_install() {
 	cd "${BUILD_DIR}/lib"
+	if [[ ${CHOST} == *darwin* ]] ; then
+		dolib.so libc++*dylib
+		return
+	fi
+
 	if use static-libs ; then
 		dolib.a libc++.a
 		gen_static_ldscript
@@ -156,6 +219,9 @@ 
 
 multilib_src_install_all() {
 	einstalldocs
+	# libc++abi needs the libc++ headers and we need libc++abi so the headers
+	# are already installed
+	[[ ${CHOST} == *darwin* ]] && return
 	insinto /usr/include/c++/v1
 	doins -r include/*
 }