diff --git a/0001-Use-jobserver-on-LTO-from-make.patch b/0001-Use-jobserver-on-LTO-from-make.patch
new file mode 100644
index 0000000..c8310c3
--- /dev/null
+++ b/0001-Use-jobserver-on-LTO-from-make.patch
@@ -0,0 +1,33 @@
+From c87570aad9f4675f2bba9233f12f53d9fa287c51 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Chv=C3=A1tal?= <tchvatal@suse.com>
+Date: Fri, 6 Apr 2018 16:33:39 +0200
+Subject: [PATCH] Use jobserver on LTO from make
+
+This should avoid executing PARALELISM threads for each linker call but
+rather limits it to the basic jobs given to make.
+
+Previous behaviour could be 8 make threads, each spawning 8 LTO threads,
+while here it should append its jobs to make and leave it to the make
+itself to distribute.
+
+Change-Id: Ib22bd21dfae60eb0eb8ac7b9c1c277b152378294
+---
+ solenv/gbuild/platform/com_GCC_defs.mk | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/solenv/gbuild/platform/com_GCC_defs.mk b/solenv/gbuild/platform/com_GCC_defs.mk
+index ac3cbc366cf7..4180144bdec4 100644
+--- a/solenv/gbuild/platform/com_GCC_defs.mk
++++ b/solenv/gbuild/platform/com_GCC_defs.mk
+@@ -158,7 +158,7 @@ ifeq ($(COM_IS_CLANG),TRUE)
+ gb_LTOFLAGS := -flto
+ gb_LTOPLUGINFLAGS := --plugin LLVMgold.so
+ else
+-gb_LTOFLAGS := -flto=$(PARALLELISM) -fuse-linker-plugin -O2
++gb_LTOFLAGS := -flto=jobserver -fuse-linker-plugin -O2
+ endif
+ endif
+ 
+-- 
+2.16.3
+
diff --git a/libreoffice.changes b/libreoffice.changes
index 1e23485..ee6075e 100644
--- a/libreoffice.changes
+++ b/libreoffice.changes
@@ -1,3 +1,10 @@
+-------------------------------------------------------------------
+Fri Apr  6 14:27:40 UTC 2018 - tchvatal@suse.com
+
+- Switch to memory-constraints macros to limit threads as needed
+- Enable LTO on libreoffice, 16% smaller binaries, less memory used:
+  * 0001-Use-jobserver-on-LTO-from-make.patch
+
 -------------------------------------------------------------------
 Tue Apr  3 12:26:41 UTC 2018 - tchvatal@suse.com
 
diff --git a/libreoffice.spec b/libreoffice.spec
index 05aeea1..9a6a275 100644
--- a/libreoffice.spec
+++ b/libreoffice.spec
@@ -97,6 +97,8 @@ Patch5:         0001-Use-PYTHON_FOR_BUILD-instead-of-calling-python-direc.patch
 Patch7:         bnc1039203.patch
 # LO-L3: Slide with chart has some strange (too large?) elements (PPTX)
 Patch8:         bnc1060128.patch
+# Upstream! this uses jobserver instead of PARALELISM for LTO
+Patch9:         0001-Use-jobserver-on-LTO-from-make.patch
 # try to save space by using hardlinks
 Patch990:       install-with-hardlinks.diff
 BuildRequires:  %{name}-share-linker
@@ -140,6 +142,7 @@ BuildRequires:  libserializer
 BuildRequires:  libtool
 BuildRequires:  lpsolve-devel
 BuildRequires:  make
+BuildRequires:  memory-constraints
 BuildRequires:  neon-devel >= 0.26.0
 BuildRequires:  openldap2-devel
 BuildRequires:  pentaho-libxml
@@ -883,6 +886,7 @@ Provides additional %{langname} translations and resources for %{project}. \
 %patch5 -p1
 %patch7 -p1
 %patch8 -p1
+%patch9 -p1
 %patch990 -p1
 
 # Disable some of the failing tests (some are random)
@@ -913,23 +917,7 @@ lo_jobs="%{?jobs:%{jobs}}"
     %endif
 %endif
 # do not eat all memory
-echo "Available memory:"
-cat /proc/meminfo
-echo "System limits:"
-ulimit -a
-lo_jobs_reduced=
-if test -n "$lo_jobs" -a "$lo_jobs" -gt 1 ; then
-    mem_per_process=1200000
-    max_mem=$(awk '/MemTotal/ { print $2 }' /proc/meminfo)
-    max_jobs="$(($max_mem / $mem_per_process))"
-    test "$lo_jobs" -gt "$max_jobs" && lo_jobs="$max_jobs" && lo_jobs_reduced="yes" && echo "Warning: Reducing number of jobs to $max_jobs because of memory limits"
-    test "$lo_jobs" -le 0 && lo_jobs=1 && echo "Warning: Do not use the parallel build at all becuse of memory limits"
-fi
-# finally set jobs
-PARALLEL_BUILD=
-if test -n "$lo_jobs" ; then
-  PARALLEL_BUILD="--with-parallelism=$lo_jobs"
-fi
+%limit_build -m 1200
 # make sure that JAVA_HOME is set correctly
 source %{_sysconfdir}/profile.d/alljava.sh
 # use RPM_OPT_FLAGS, ...
@@ -954,8 +942,9 @@ google_default_client_secret="KDTRKEZk2jwT_7CDpcmMA--P"
 export NOCONFIGURE=yes
 ./autogen.sh
 %configure \
-        $PARALLEL_BUILD \
+        --with-parallelism=%{jobs} \
         --enable-eot \
+        --enable-lto \
         --enable-mergelibs \
         --docdir=%{_docdir}/%{name} \
         --with-compat-oowrappers \