# Author: Alecsandru Patrascu <alecsandru.patrascu@intel.com>

diff -r e3dea2e4f93d Makefile.pre.in
--- a/Makefile.pre.in	Mon Nov 23 08:50:20 2015 +0200
+++ b/Makefile.pre.in	Mon Nov 23 15:54:52 2015 +0200
@@ -47,6 +47,7 @@
 LLVM_PROF_MERGER=@LLVM_PROF_MERGER@
 LLVM_PROF_FILE=@LLVM_PROF_FILE@
 LLVM_PROF_ERR=@LLVM_PROF_ERR@
+LTOFLAGS=@LTOFLAGS@
 
 GNULD=          @GNULD@
 
@@ -73,12 +74,12 @@
 # Compiler options
 OPT=		@OPT@
 BASECFLAGS=	@BASECFLAGS@
-CFLAGS=		$(BASECFLAGS) @CFLAGS@ $(OPT) $(EXTRA_CFLAGS)
+CFLAGS=		$(BASECFLAGS) @CFLAGS@ $(OPT) $(LTOFLAGS) $(EXTRA_CFLAGS)
 # Both CPPFLAGS and LDFLAGS need to contain the shell's value for setup.py to
 # be able to build extension modules using the directories specified in the
 # environment variables
 CPPFLAGS=	-I. -IInclude -I$(srcdir)/Include @CPPFLAGS@
-LDFLAGS=	@LDFLAGS@
+LDFLAGS=	@LDFLAGS@ $(LTOFLAGS)
 LDLAST=		@LDLAST@
 SGI_ABI=	@SGI_ABI@
 CCSHARED=	@CCSHARED@
@@ -445,7 +446,7 @@
 	$(MAKE) profile-removal
 
 build_all_generate_profile:
-	$(MAKE) all CFLAGS="$(CFLAGS) $(PGO_PROF_GEN_FLAG)" LDFLAGS="$(LDFLAGS) $(PGO_PROF_GEN_FLAG)" LIBS="$(LIBS)"
+	$(MAKE) all CFLAGS="$(CFLAGS) $(PGO_PROF_GEN_FLAG) $(LTOFLAGS)" LDFLAGS="$(LDFLAGS) $(PGO_PROF_GEN_FLAG) $(LTOFLAGS)" LIBS="$(LIBS)"
 
 run_profile_task:
 	: # FIXME: can't run for a cross build
@@ -455,7 +456,7 @@
 	$(LLVM_PROF_MERGER)
 
 build_all_use_profile:
-	$(MAKE) all CFLAGS="$(CFLAGS) $(PGO_PROF_USE_FLAG)"
+	$(MAKE) all CFLAGS="$(CFLAGS) $(PGO_PROF_USE_FLAG) $(LTOFLAGS)" LDFLAGS="$(LDFLAGS) $(LTOFLAGS)"
 
 coverage:
 	@echo "Building with support for coverage checking:"
diff -r e3dea2e4f93d configure
--- a/configure	Mon Nov 23 08:50:20 2015 +0200
+++ b/configure	Mon Nov 23 15:54:52 2015 +0200
@@ -667,6 +667,7 @@
 LLVM_PROF_MERGER
 PGO_PROF_USE_FLAG
 PGO_PROF_GEN_FLAG
+LTOFLAGS
 UNIVERSAL_ARCH_FLAGS
 BASECFLAGS
 OPT
@@ -794,6 +795,7 @@
 enable_shared
 enable_profiling
 with_pydebug
+with_lto
 enable_toolbox_glue
 with_libs
 with_system_expat
@@ -1474,6 +1476,7 @@
                           compiler
   --with-suffix=.exe      set executable suffix
   --with-pydebug          build with Py_DEBUG defined
+  --with-lto              Enable Link Time Optimizations. Disabled by default.
   --with-libs='lib1 ...'  link against additional libs
   --with-system-expat     build pyexpat module using an installed expat
                           library
@@ -6333,6 +6336,39 @@
 fi
 
 
+# Enable LTO flags
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for --with-lto" >&5
+$as_echo_n "checking for --with-lto... " >&6; }
+# Check whether --with-lto was given.
+if test "${with_lto+set}" = set; then :
+  withval=$with_lto;
+if test "$withval" != no
+then
+  case $CC in
+    *clang*)
+      # Any changes made here should be reflected in the GCC+Darwin case below
+      LTOFLAGS="-flto"
+      ;;
+    *gcc*)
+      case $ac_sys_system in
+        Darwin*)
+          LTOFLAGS="-flto"
+          ;;
+        *)
+          LTOFLAGS="-flto -fuse-linker-plugin -ffat-lto-objects -flto-partition=none"
+          ;;
+      esac
+      ;;
+  esac
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; };
+fi
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
 # Enable PGO flags.
 # Extract the first word of "llvm-profdata", so it can be a program name with args.
 set dummy llvm-profdata; ac_word=$2
diff -r e3dea2e4f93d configure.ac
--- a/configure.ac	Mon Nov 23 08:50:20 2015 +0200
+++ b/configure.ac	Mon Nov 23 15:54:52 2015 +0200
@@ -1353,6 +1353,34 @@
 fi
 
 
+# Enable LTO flags
+AC_SUBST(LTOFLAGS)
+AC_MSG_CHECKING(for --with-lto)
+AC_ARG_WITH(lto, AS_HELP_STRING([--with-lto], [Enable Link Time Optimizations. Disabled by default.]),
+[
+if test "$withval" != no
+then
+  case $CC in
+    *clang*)
+      # Any changes made here should be reflected in the GCC+Darwin case below
+      LTOFLAGS="-flto"
+      ;;
+    *gcc*)
+      case $ac_sys_system in
+        Darwin*)
+          LTOFLAGS="-flto"
+          ;;
+        *)
+          LTOFLAGS="-flto -fuse-linker-plugin -ffat-lto-objects -flto-partition=none"
+          ;;
+      esac
+      ;;
+  esac
+  AC_MSG_RESULT(yes);
+fi],
+[AC_MSG_RESULT(no)])
+
+
 # Enable PGO flags.
 AC_SUBST(PGO_PROF_GEN_FLAG)
 AC_SUBST(PGO_PROF_USE_FLAG)