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

diff -r 59f33f4249ec Makefile.pre.in
--- a/Makefile.pre.in	Sun Nov 22 23:46:02 2015 -0800
+++ b/Makefile.pre.in	Mon Nov 23 16:19:31 2015 +0200
@@ -48,6 +48,7 @@
 LLVM_PROF_MERGER=@LLVM_PROF_MERGER@
 LLVM_PROF_FILE=@LLVM_PROF_FILE@
 LLVM_PROF_ERR=@LLVM_PROF_ERR@
+LTOFLAGS=@LTOFLAGS@
 
 GNULD=		@GNULD@
 
@@ -75,13 +76,13 @@
 OPT=		@OPT@
 BASECFLAGS=	@BASECFLAGS@
 BASECPPFLAGS=	@BASECPPFLAGS@
-CONFIGURE_CFLAGS=	@CFLAGS@
+CONFIGURE_CFLAGS=	@CFLAGS@ $(LTOFLAGS)
 # CFLAGS_NODIST is used for building the interpreter and stdlib C extensions.
 # Use it when a compiler flag should _not_ be part of the distutils CFLAGS
 # once Python is installed (Issue #21121).
-CONFIGURE_CFLAGS_NODIST=@CFLAGS_NODIST@
-CONFIGURE_CPPFLAGS=	@CPPFLAGS@
-CONFIGURE_LDFLAGS=	@LDFLAGS@
+CONFIGURE_CFLAGS_NODIST=@CFLAGS_NODIST@ $(LTOFLAGS)
+CONFIGURE_CPPFLAGS=	@CPPFLAGS@ $(LTOFLAGS)
+CONFIGURE_LDFLAGS=	@LDFLAGS@ $(LTOFLAGS)
 # Avoid assigning CFLAGS, LDFLAGS, etc. so users can use them on the
 # command line to append to these values without stomping the pre-set
 # values.
diff -r 59f33f4249ec configure
--- a/configure	Sun Nov 22 23:46:02 2015 -0800
+++ b/configure	Mon Nov 23 16:19:31 2015 +0200
@@ -673,6 +673,7 @@
 LLVM_PROF_MERGER
 PGO_PROF_USE_FLAG
 PGO_PROF_GEN_FLAG
+LTOFLAGS
 ABIFLAGS
 LN
 MKDIR_P
@@ -806,6 +807,7 @@
 enable_shared
 enable_profiling
 with_pydebug
+with_lto
 with_hash_algorithm
 with_address_sanitizer
 with_libs
@@ -1485,6 +1487,7 @@
                           compiler
   --with-suffix=.exe      set executable suffix
   --with-pydebug          build with Py_DEBUG defined
+  --with-lto              Enable Link Time Optimizations. Disabled by default.
   --with-hash-algorithm=[fnv|siphash24]
                           select hash algorithm
   --with-address-sanitizer
@@ -6437,6 +6440,39 @@
 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 59f33f4249ec configure.ac
--- a/configure.ac	Sun Nov 22 23:46:02 2015 -0800
+++ b/configure.ac	Mon Nov 23 16:19:31 2015 +0200
@@ -1218,6 +1218,34 @@
 fi],
 [AC_MSG_RESULT(no)])
 
+# 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)