Index: Mk/Uses/qt-dist.mk
===================================================================
--- Mk/Uses/qt-dist.mk	(revision 480666)
+++ Mk/Uses/qt-dist.mk	(working copy)
@@ -196,6 +196,10 @@
 _EXTRA_PATCHES_QT5=	${PORTSDIR}/devel/${_QT_RELNAME}/files/extrapatch-mkspecs_features_create__cmake.prf \
 			${PORTSDIR}/devel/${_QT_RELNAME}/files/extrapatch-mkspecs_features_qt__module.prf \
 			${PORTSDIR}/devel/${_QT_RELNAME}/files/extrapatch-mkspecs_common_bsd_bsd.conf
+.        if ${ARCH:Mmips*} || ${ARCH:Mpowerpc*} || ${ARCH} == sparc64
+_EXTRA_PATCHES_QT5+=	${PORTSDIR}/devel/${_QT_RELNAME}/files/extra-patch-mkspecs_common_g++-base.conf \
+			${PORTSDIR}/devel/${_QT_RELNAME}/files/extra-patch-mkspecs_common_gcc-base.conf
+.        endif
 .    endif
 EXTRA_PATCHES?=		${PORTSDIR}/devel/${_QT_RELNAME}/files/extrapatch-configure \
 			${_EXTRA_PATCHES_QT4} ${_EXTRA_PATCHES_QT5}
@@ -268,6 +272,14 @@
 # other QtBase ports. See below.
 _QT5_BASE=		core dbus gui network sql widgets
 
+.if ${_QT_VER:M5}
+post-patch: gcc-post-patch
+gcc-post-patch:
+	${REINPLACE_CMD} 's|%%LOCALBASE%%|${LOCALBASE}|' ${WRKSRC}/mkspecs/common/gcc-base.conf
+	${REINPLACE_CMD} 's|%%GCC_DEFAULT%%|${GCC_DEFAULT}|' ${WRKSRC}/mkspecs/common/gcc-base.conf \
+		${WRKSRC}/mkspecs/common/g++-base.conf
+.endif
+
 pre-configure: qtbase-pre-configure
 qtbase-pre-configure:
 .      for tool in ${_QT_TOOLS}
Index: devel/qt5/files/extra-patch-mkspecs_common_g++-base.conf
===================================================================
--- devel/qt5/files/extra-patch-mkspecs_common_g++-base.conf	(nonexistent)
+++ devel/qt5/files/extra-patch-mkspecs_common_g++-base.conf	(working copy)
@@ -0,0 +1,20 @@
+--- mkspecs/common/g++-base.conf.orig	2018-09-21 12:02:35 UTC
++++ mkspecs/common/g++-base.conf
+@@ -8,14 +8,14 @@
+ # you can use the manual test in tests/manual/mkspecs.
+ #
+ 
+-QMAKE_COMPILER          = gcc
++QMAKE_COMPILER          = gcc%%GCC_DEFAULT%%
+ 
+-QMAKE_CC                = gcc
++QMAKE_CC                = gcc%%GCC_DEFAULT%%
+ 
+ QMAKE_LINK_C            = $$QMAKE_CC
+ QMAKE_LINK_C_SHLIB      = $$QMAKE_CC
+ 
+-QMAKE_CXX               = g++
++QMAKE_CXX               = g++%%GCC_DEFAULT%%
+ 
+ QMAKE_LINK              = $$QMAKE_CXX
+ QMAKE_LINK_SHLIB        = $$QMAKE_CXX

Property changes on: devel/qt5/files/extra-patch-mkspecs_common_g++-base.conf
___________________________________________________________________
Added: fbsd:nokeywords
## -0,0 +1 ##
+yes
\ No newline at end of property
Added: svn:eol-style
## -0,0 +1 ##
+native
\ No newline at end of property
Added: svn:mime-type
## -0,0 +1 ##
+text/plain
\ No newline at end of property
Index: devel/qt5/files/extra-patch-mkspecs_common_gcc-base.conf
===================================================================
--- devel/qt5/files/extra-patch-mkspecs_common_gcc-base.conf	(nonexistent)
+++ devel/qt5/files/extra-patch-mkspecs_common_gcc-base.conf	(working copy)
@@ -0,0 +1,11 @@
+--- mkspecs/common/gcc-base.conf.orig	2018-09-21 12:20:28 UTC
++++ mkspecs/common/gcc-base.conf
+@@ -73,7 +73,7 @@ QMAKE_CXXFLAGS_LTCG        = $$QMAKE_CFLAGS_LTCG
+ QMAKE_CXXFLAGS_LTCG_FATOBJECTS = $$QMAKE_CFLAGS_LTCG_FATOBJECTS
+ QMAKE_CXXFLAGS_DISABLE_LTCG   = $$QMAKE_CFLAGS_DISABLE_LTCG
+ 
+-QMAKE_LFLAGS           +=
++QMAKE_LFLAGS           += -Wl,-rpath=%%LOCALBASE%%/lib/gcc%%GCC_DEFAULT%%
+ QMAKE_LFLAGS_DEBUG     +=
+ QMAKE_LFLAGS_APP       +=
+ QMAKE_LFLAGS_RELEASE   +=

Property changes on: devel/qt5/files/extra-patch-mkspecs_common_gcc-base.conf
___________________________________________________________________
Added: fbsd:nokeywords
## -0,0 +1 ##
+yes
\ No newline at end of property
Added: svn:eol-style
## -0,0 +1 ##
+native
\ No newline at end of property
Added: svn:mime-type
## -0,0 +1 ##
+text/plain
\ No newline at end of property
Index: devel/qt5-qmake/Makefile
===================================================================
--- devel/qt5-qmake/Makefile	(revision 480666)
+++ devel/qt5-qmake/Makefile	(working copy)
@@ -30,8 +30,6 @@
 QMAKESPEC=	freebsd-${QMAKE_COMPILER}
 INSTALL_TARGET=	sub-qmake-qmake-aux-pro-install_subtargets install_mkspecs
 
-BROKEN_powerpc64=	fails to compile: error: unrecognized command line option -std=c++11
-
 BUILD_WRKSRC=	${WRKSRC}/${PORTNAME}
 
 post-patch: