diff --git a/media-libs/x265/metadata.xml b/media-libs/x265/metadata.xml
index ed61a9259d5f1..534499f3593e9 100644
--- a/media-libs/x265/metadata.xml
+++ b/media-libs/x265/metadata.xml
@@ -9,6 +9,7 @@
     <flag name="12bit">Add support for producing 12bits HEVC.</flag>
     <flag name="numa">Build with support for NUMA nodes.</flag>
     <flag name="pic">Disable optimized assembly code that is not PIC friendly</flag>
+	<flag name="power8">Enable support for Power 8 assembly optimizations.</flag>
   </use>
   <upstream>
     <remote-id type="bitbucket">multicoreware/x265</remote-id>
diff --git a/media-libs/x265/x265-2.2.ebuild b/media-libs/x265/x265-2.2.ebuild
index 31477382476f1..379c18e775a6a 100644
--- a/media-libs/x265/x265-2.2.ebuild
+++ b/media-libs/x265/x265-2.2.ebuild
@@ -21,7 +21,7 @@ HOMEPAGE="http://x265.org/"
 LICENSE="GPL-2"
 # subslot = libx265 soname
 SLOT="0/102"
-IUSE="+10bit +12bit neon numa pic test"
+IUSE="+10bit +12bit neon numa pic power8 test"
 
 ASM_DEPEND=">=dev-lang/yasm-1.2.0"
 RDEPEND="numa? ( >=sys-process/numactl-2.0.10-r1[${MULTILIB_USEDEP}] )"
@@ -139,6 +139,8 @@ multilib_src_configure() {
 		$(cmake-utils_use_enable test TESTS)
 		$(multilib_is_native_abi || echo "-DENABLE_CLI=OFF")
 		-DENABLE_LIBNUMA=$(usex numa ON OFF)
+		-DCPU_POWER8=$(usex power8 ON OFF)
+		-DENABLE_ALTIVEC=$(usex power8 ON OFF)
 		-DLIB_INSTALL_DIR="$(get_libdir)"
 	)
 
diff --git a/media-libs/x265/x265-2.3.ebuild b/media-libs/x265/x265-2.3.ebuild
index 6a97b960617f6..ed35ad6d51044 100644
--- a/media-libs/x265/x265-2.3.ebuild
+++ b/media-libs/x265/x265-2.3.ebuild
@@ -21,7 +21,7 @@ HOMEPAGE="http://x265.org/"
 LICENSE="GPL-2"
 # subslot = libx265 soname
 SLOT="0/110"
-IUSE="+10bit +12bit neon numa pic test"
+IUSE="+10bit +12bit neon numa pic power8 test"
 
 ASM_DEPEND=">=dev-lang/yasm-1.2.0"
 RDEPEND="numa? ( >=sys-process/numactl-2.0.10-r1[${MULTILIB_USEDEP}] )"
@@ -139,6 +139,8 @@ multilib_src_configure() {
 		$(cmake-utils_use_enable test TESTS)
 		$(multilib_is_native_abi || echo "-DENABLE_CLI=OFF")
 		-DENABLE_LIBNUMA=$(usex numa ON OFF)
+		-DCPU_POWER8=$(usex power8 ON OFF)
+		-DENABLE_ALTIVEC=$(usex power8 ON OFF)
 		-DLIB_INSTALL_DIR="$(get_libdir)"
 	)
 
diff --git a/media-libs/x265/x265-9999.ebuild b/media-libs/x265/x265-9999.ebuild
index 5efa377f90f14..65e1f961e6554 100644
--- a/media-libs/x265/x265-9999.ebuild
+++ b/media-libs/x265/x265-9999.ebuild
@@ -21,7 +21,7 @@ HOMEPAGE="http://x265.org/"
 LICENSE="GPL-2"
 # subslot = libx265 soname
 SLOT="0/111"
-IUSE="+10bit +12bit neon numa pic test"
+IUSE="+10bit +12bit neon numa pic power8 test"
 
 ASM_DEPEND=">=dev-lang/yasm-1.2.0"
 RDEPEND="numa? ( >=sys-process/numactl-2.0.10-r1[${MULTILIB_USEDEP}] )"
@@ -139,6 +139,8 @@ multilib_src_configure() {
 		$(cmake-utils_use_enable test TESTS)
 		$(multilib_is_native_abi || echo "-DENABLE_CLI=OFF")
 		-DENABLE_LIBNUMA=$(usex numa ON OFF)
+		-DCPU_POWER8=$(usex power8 ON OFF)
+		-DENABLE_ALTIVEC=$(usex power8 ON OFF)
 		-DLIB_INSTALL_DIR="$(get_libdir)"
 	)