--- /usr/portage/sys-devel/llvm/llvm-3.7.1.ebuild	2016-01-09 19:01:02.000000000 +0000
+++ llvm-3.7.1.ebuild	2016-01-20 21:11:18.701967929 +0000
@@ -370,6 +370,21 @@
 		#filter-flags -msahf -frecord-gcc-switches
 	fi
 
+	if tc-is-cross-compiler; then
+		mycmakeargs+=(
+			-DCMAKE_CROSSCOMPILING=True \
+			-DLLVM_TABLEGEN=/usr/bin/llvm-tblgen \
+			-DCMAKE_CXX_FLAGS="-I${EROOT}usr/include/"
+		)
+
+		if use clang; then
+			mycmakeargs+=(
+				-DCLANG_TABLEGEN=/usr/bin/clang-tblgen
+				-DLLVM_ENABLE_PIC=False # Work around. See http://llvm.org/docs/HowToCrossCompileLLVM.html
+			)
+		fi
+	fi
+
 	cmake-utils_src_configure
 }