diff --git a/debian/changelog b/debian/changelog
index fff2aff6..d9dc2699 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,8 +1,14 @@
-llvm-toolchain-5.0 (1:5.0-1ubuntu1) artful; urgency=medium
+llvm-toolchain-5.0 (1:5.0-2) unstable; urgency=medium
 
+  [ Matthias Klose ]
   * Link with --no-keep-files-mapped --no-map-whole-files when using gold.
+  * build using gold on arm64 and s390x. For backports, arm64 might still
+    need the BFD linker, and building with only one or two processes in
+    parallel.
+  * On amd64, s390x, arm64 and ppc64el, build with -g1 instead of -g.
+  * Set CMAKE_CXX_FLAGS_RELWITHDEBINFO and pass opt_flags.
 
- -- Matthias Klose <doko@ubuntu.com>  Fri, 08 Sep 2017 10:43:24 +0200
+ -- Sylvestre Ledru <sylvestre@debian.org>  Mon, 18 Sep 2017 21:53:00 +0200
 
 llvm-toolchain-5.0 (1:5.0-1) unstable; urgency=medium
 
diff --git a/debian/control b/debian/control
index 5231d68e..ea6cc005 100644
--- a/debian/control
+++ b/debian/control
@@ -229,6 +229,8 @@ Section: libs
 Depends: ${shlibs:Depends}, ${misc:Depends}
 Pre-Depends: ${misc:Pre-Depends}
 Multi-Arch: same
+Breaks: libllvm3.9v4
+Replaces: libllvm3.9v4
 Description: Modular compiler and toolchain technologies, runtime library
  LLVM is a collection of libraries and tools that make it easy to build
  compilers, optimizers, just-in-time code generators, and many other
@@ -243,6 +245,8 @@ Priority: extra
 Depends: ${shlibs:Depends}, ${misc:Depends}, libllvm5.0 (= ${binary:Version})
 Pre-Depends: ${misc:Pre-Depends}
 Multi-Arch: same
+Breaks: libllvm3.9v4-dbg
+Replaces: libllvm3.9v4-dbg
 Description: Modular compiler and toolchain technologies, debugging libraries
  LLVM is a collection of libraries and tools that make it easy to build
  compilers, optimizers, just-in-time code generators, and many other
diff --git a/debian/rules b/debian/rules
index 515e5920..ace6d715 100755
--- a/debian/rules
+++ b/debian/rules
@@ -61,6 +61,9 @@ export CC=gcc-$(GCC_VERSION)
 export CXX=g++-$(GCC_VERSION)
 
 opt_flags = -g -O2
+ifneq (,$(filter $(DEB_HOST_ARCH),amd64 arm64 ppc64el s390x))
+  opt_flags = -g1 -O2
+endif
 ifneq (,$(findstring $(DEB_HOST_ARCH),armel))
   opt_flags += -marm
   # 3.8 fails to build, disable the compiler_rt builtins
@@ -81,7 +84,7 @@ else
 	control_vars = '-Vdep:devlibs=libstdc++6-$(GCC_VERSION)-dev'
 endif
 
-BINUTILS_GOLD_ARCHS := amd64 armhf i386 powerpcspe ppc64 ppc64el sparc sparc64 x32
+BINUTILS_GOLD_ARCHS := amd64 arm64 armhf i386 powerpcspe ppc64 ppc64el sparc sparc64 x32 s390x
 ifeq ($(shell dpkg --compare-versions $(shell dpkg-query -W -f '$${Version}' binutils) ge 2.23.1-1~exp3 ; echo $$?),0)
 ifneq (,$(filter $(DEB_HOST_ARCH),$(BINUTILS_GOLD_ARCHS)))
 # -fused-ld=gold enables the gold linker (but is not supported by all archs / distro)
@@ -274,6 +277,7 @@ override_dh_auto_configure: preconfigure
 	-DCMAKE_INSTALL_PREFIX=/usr/lib/llvm-$(LLVM_VERSION) \
 	-DCMAKE_VERBOSE_MAKEFILE=ON \
 	-DCMAKE_BUILD_TYPE=RelWithDebInfo \
+	-DCMAKE_CXX_FLAGS_RELWITHDEBINFO="$(opt_flags)" \
 	-DCMAKE_CXX_FLAGS='$(CXXFLAGS_EXTRA)' \
 	-DLLVM_LINK_LLVM_DYLIB=ON \
 	-DLLVM_INSTALL_UTILS=ON \