Index: Mk/Uses/compiler.mk
===================================================================
--- Mk/Uses/compiler.mk
+++ Mk/Uses/compiler.mk
@@ -96,8 +96,28 @@
 
 .if ${_COMPILER_ARGS:Mopenmp}
 .if ${COMPILER_TYPE} == clang
-USE_GCC=	yes
+.if ${ARCH} == amd64
+_USES_POST+=	localbase:ldflags
+.if ${COMPILER_VERSION} < 38
+BUILD_DEPENDS+=	llvm40>=0:devel/llvm40
+CPP=	${LOCALBASE}/bin/clang-cpp40
+CC=	${LOCALBASE}/bin/clang40
+CXX=	${LOCALBASE}/bin/clang++40
+CHOSEN_COMPILER_TYPE=	clang
+.endif
+LIB_DEPENDS+=	libomp.so.0:devel/openmp
+.else
+USE_GCC=		yes
 CHOSEN_COMPILER_TYPE=	gcc
+.if ${COMPILER_FEATURES:Mlibc++}
+CXXFLAGS+=	-nostdinc++ -isystem /usr/include/c++/v1
+LDFLAGS+=	-L${WRKDIR}
+
+_USES_configure+=	200:gcc-libc++-configure
+gcc-libc++-configure:
+	@${LN} -fs /usr/lib/libc++.so ${WRKDIR}/libstdc++.so
+.endif
+.endif
 .endif
 .endif
 
Index: devel/llvm40/Makefile
===================================================================
--- devel/llvm40/Makefile
+++ devel/llvm40/Makefile
@@ -2,7 +2,7 @@
 
 PORTNAME=	llvm
 DISTVERSION=	4.0.0
-PORTREVISION=	4
+PORTREVISION=	5
 CATEGORIES=	devel lang
 MASTER_SITES=	http://llvm.org/${PRE_}releases/${LLVM_RELEASE}/${RCDIR}
 PKGNAMESUFFIX=	${LLVM_SUFFIX}
@@ -344,6 +344,7 @@
 	    -e 's|lit\.|lit${LLVM_SUFFIX}.|' \
 	    ${WRKSRC}/utils/lit/lit.py ${WRKSRC}/utils/lit/lit/*.py \
 	    ${WRKSRC}/utils/lit/lit/formats/*.py
+	    ${REINPLACE_CMD} -e 's|CMAKE_INSTALL_PREFIX|${CMAKE_INSTALL_PREFIX}|g' ${WRKSRC}/tools/clang/lib/Driver/Tools.cpp
 
 post-patch-CLANG-on:
 	${REINPLACE_CMD} -e 's|%%LLVM_PREFIX%%|${LLVM_PREFIX}|' \
Index: devel/llvm40/files/clang-patch-fopenmp.diff
===================================================================
--- devel/llvm40/files/clang-patch-fopenmp.diff
+++ devel/llvm40/files/clang-patch-fopenmp.diff
@@ -1,32 +1,35 @@
---- tools/clang/lib/Driver/Tools.cpp.orig	2017-01-26 08:40:33.955918000 +0000
-+++ tools/clang/lib/Driver/Tools.cpp	2017-01-26 09:41:36.791095000 +0000
-@@ -3216,13 +3216,22 @@
+--- tools/clang/lib/Driver/Tools.cpp.orig	2017-04-15 22:54:19.427146000 -0400
++++ tools/clang/lib/Driver/Tools.cpp	2017-04-15 23:10:14.340304000 -0400
+@@ -3216,13 +3216,25 @@
  
    switch (TC.getDriver().getOpenMPRuntime(Args)) {
    case Driver::OMPRT_OMP:
 -    CmdArgs.push_back("-lomp");
-+    if (TC.getTriple().getOS() != llvm::Triple::FreeBSD || TC.isCrossCompiling() || !llvm::sys::fs::exists("/usr/local/llvm40/lib/libomp.so"))
++    if (TC.getTriple().getOS() != llvm::Triple::FreeBSD || TC.isCrossCompiling() || !llvm::sys::fs::exists("/usr/local/llvm40/lib/libomp.so")){
++      CmdArgs.push_back("-LCMAKE_INSTALL_PREFIX/lib");
 +      CmdArgs.push_back("-lomp");
-+    else
++    } else
 +      CmdArgs.push_back("/usr/local/llvm40/lib/libomp.so");
      break;
    case Driver::OMPRT_GOMP:
 -    CmdArgs.push_back("-lgomp");
-+    if (TC.getTriple().getOS() != llvm::Triple::FreeBSD || TC.isCrossCompiling() || !llvm::sys::fs::exists("/usr/local/llvm40/lib/libgomp.so"))
++    if (TC.getTriple().getOS() != llvm::Triple::FreeBSD || TC.isCrossCompiling() || !llvm::sys::fs::exists("/usr/local/llvm40/lib/libgomp.so")){
++      CmdArgs.push_back("-LCMAKE_INSTALL_PREFIX/lib");
 +      CmdArgs.push_back("-lgomp");
-+    else
++    } else
 +      CmdArgs.push_back("/usr/local/llvm40/lib/libgomp.so");
      break;
    case Driver::OMPRT_IOMP5:
 -    CmdArgs.push_back("-liomp5");
-+    if (TC.getTriple().getOS() != llvm::Triple::FreeBSD || TC.isCrossCompiling() || !llvm::sys::fs::exists("/usr/local/llvm40/lib/libiomp5.so"))
++    if (TC.getTriple().getOS() != llvm::Triple::FreeBSD || TC.isCrossCompiling() || !llvm::sys::fs::exists("/usr/local/llvm40/lib/libiomp5.so")){
++      CmdArgs.push_back("-LCMAKE_INSTALL_PREFIX/lib");
 +      CmdArgs.push_back("-liomp5");
-+    else
++    } else
 +      CmdArgs.push_back("/usr/local/llvm40/lib/libiomp5.so");
      break;
    case Driver::OMPRT_Unknown:
      // Already diagnosed.
-@@ -10235,17 +10244,26 @@
+@@ -10239,17 +10251,26 @@
          // Also link the particular OpenMP runtimes.
          switch (ToolChain.getDriver().getOpenMPRuntime(Args)) {
          case Driver::OMPRT_OMP:
Index: math/openblas/Makefile
===================================================================
--- math/openblas/Makefile
+++ math/openblas/Makefile
@@ -73,6 +73,7 @@
 .endif
 
 .if ${PORT_OPTIONS:MOPENMP}
+USE_GCC=	yes
 USES+=		compiler:openmp
 BUILDFLAGS_THREAD+=	USE_OPENMP=1
 .endif