diff -r c49ff8dbf907 configure.ac
--- a/configure.ac	Wed Sep 07 01:21:14 2016 +0200
+++ b/configure.ac	Tue Sep 06 16:56:47 2016 -0700
@@ -1282,6 +1282,37 @@
 fi],
 [AC_MSG_RESULT(no)])
 
+# Enable optimization flags
+AC_SUBST(DEF_MAKE_ALL_RULE)
+AC_SUBST(DEF_MAKE_RULE)
+Py_OPT='false'
+AC_MSG_CHECKING(for --with-optimizations)
+AC_ARG_WITH(optimizations, AS_HELP_STRING([--with-optimizations], [Enable all optimizations  when available (LTO, PGO, etc). Disabled by default.]),
+[
+if test "$withval" != no
+then
+  Py_OPT='true'
+  AC_MSG_RESULT(yes);
+else
+  Py_OPT='false'
+  AC_MSG_RESULT(no);
+fi],
+[AC_MSG_RESULT(no)])
+if test "$Py_OPT" = 'true' ; then
+  Py_LTO='true'
+  case $ac_sys_system in
+    Darwin*)
+      # At least on macOS El Capitan, LTO does not work with PGO.
+      Py_LTO='false'
+      ;;
+    esac
+  DEF_MAKE_ALL_RULE="profile-opt"
+  DEF_MAKE_RULE="build_all"
+else
+  DEF_MAKE_ALL_RULE="build_all"
+  DEF_MAKE_RULE="all"
+fi
+
 # Enable LTO flags
 AC_SUBST(LTOFLAGS)
 AC_MSG_CHECKING(for --with-lto)
@@ -5337,3 +5368,13 @@
 			-s Modules Modules/Setup.config \
 			Modules/Setup.local Modules/Setup
 mv config.c Modules
+
+if test "$Py_OPT" = 'false' -a "$Py_DEBUG" != 'true'; then
+    echo "" >&AS_MESSAGE_FD
+    echo "" >&AS_MESSAGE_FD
+    echo "If you want a release build with all optimizations active (LTO, PGO, etc),"
+    echo "please run ./configure --with-optimizations" >&AS_MESSAGE_FD
+    echo "" >&AS_MESSAGE_FD
+    echo "" >&AS_MESSAGE_FD
+fi
+