diff -r da483bda6efc Makefile.pre.in
--- a/Makefile.pre.in	Mon Aug 24 16:17:13 2015 -0400
+++ b/Makefile.pre.in	Wed Aug 26 19:11:31 2015 +0300
@@ -42,6 +42,10 @@
 HGVERSION=	@HGVERSION@
 HGTAG=		@HGTAG@
 HGBRANCH=	@HGBRANCH@
+PGO_PROF_GEN_FLAG=@PGO_PROF_GEN_FLAG@
+PGO_PROF_USE_FLAG=@PGO_PROF_USE_FLAG@
+LLVM_PROF_MERGER=@LLVM_PROF_MERGER@
+LLVM_PROF_FILE=@LLVM_PROF_FILE@
 
 GNULD=          @GNULD@
 
@@ -204,8 +208,8 @@
 TCLTK_LIBS=	@TCLTK_LIBS@
 
 # The task to run while instrument when building the profile-opt target
-PROFILE_TASK=	$(srcdir)/Tools/pybench/pybench.py -n 2 --with-gc --with-syscheck
-#PROFILE_TASK=	$(srcdir)/Lib/test/regrtest.py
+PROFILE_TASK_X86=-m test.regrtest
+PROFILE_TASK_OLD=$(srcdir)/Tools/pybench/pybench.py -n 2 --with-gc --with-syscheck
 
 # === Definitions added by makesetup ===
 
@@ -422,25 +426,38 @@
 
 # Compile a binary with gcc profile guided optimization.
 profile-opt:
+	@if [ `uname -m | grep 86` == '' ];then \
+		@echo "Profile generation was tested only on x86 architectures" ;\
+	fi
 	@echo "Building with support for profile generation:"
 	$(MAKE) clean
+	$(MAKE) profile-removal
 	$(MAKE) build_all_generate_profile
 	@echo "Running benchmark to generate profile data:"
 	$(MAKE) profile-removal
 	$(MAKE) run_profile_task
+	$(MAKE) build_all_merge_profile
 	@echo "Rebuilding with profile guided optimizations:"
 	$(MAKE) clean
 	$(MAKE) build_all_use_profile
+	$(MAKE) profile-removal
 
 build_all_generate_profile:
-	$(MAKE) all CFLAGS="$(CFLAGS) -fprofile-generate" LIBS="$(LIBS) -lgcov"
+	$(MAKE) all CFLAGS="$(CFLAGS) $(PGO_PROF_GEN_FLAG)" LDFLAGS="$(LDFLAGS) $(PGO_PROF_GEN_FLAG)" LIBS="$(LIBS)"
 
 run_profile_task:
 	: # FIXME: can't run for a cross build
-	./$(BUILDPYTHON) $(PROFILE_TASK)
+	@if [ `uname -m | grep 86` == '' ];then \
+		$(LLVM_PROF_FILE) ./$(BUILDPYTHON) $(PROFILE_TASK_OLD) || true ;\
+	else \
+		$(LLVM_PROF_FILE) ./$(BUILDPYTHON) $(PROFILE_TASK_X86) || true ;\
+	fi
+
+build_all_merge_profile:
+	$(LLVM_PROF_MERGER)
 
 build_all_use_profile:
-	$(MAKE) all CFLAGS="$(CFLAGS) -fprofile-use"
+	$(MAKE) all CFLAGS="$(CFLAGS) $(PGO_PROF_USE_FLAG)"
 
 coverage:
 	@echo "Building with support for coverage checking:"
@@ -1330,9 +1347,11 @@
 	find build -name 'fficonfig.h' -exec rm -f {} ';' || true
 	find build -name 'fficonfig.py' -exec rm -f {} ';' || true
 	-rm -f Lib/lib2to3/*Grammar*.pickle
+	-rm -rf build
 
 profile-removal:
 	find . -name '*.gc??' -exec rm -f {} ';'
+	find . -name '*.profclang?' -exec rm -f {} ';'
 
 clobber: clean profile-removal
 	-rm -f $(BUILDPYTHON) $(PGEN) $(LIBRARY) $(LDLIBRARY) $(DLLLIBRARY) \
diff -r da483bda6efc configure.ac
--- a/configure.ac	Mon Aug 24 16:17:13 2015 -0400
+++ b/configure.ac	Wed Aug 26 19:11:31 2015 +0300
@@ -1352,6 +1352,38 @@
   CFLAGS=$save_CFLAGS
 fi
 
+
+# enable PGO flags
+AC_SUBST(PGO_PROF_GEN_FLAG)
+AC_SUBST(PGO_PROF_USE_FLAG)
+AC_SUBST(LLVM_PROF_MERGER)
+AC_SUBST(LLVM_PROF_FILE)
+case $CC in
+  *clang*) 
+    PGO_PROF_GEN_FLAG="-fprofile-instr-generate"
+    PGO_PROF_USE_FLAG="-fprofile-instr-use=code.profclangd"
+    LLVM_PROF_MERGER="llvm-profdata merge -output=code.profclangd *.profclangr"
+    LLVM_PROF_FILE="LLVM_PROFILE_FILE=\"code-%p.profclangr\""
+    ;;
+  *gcc*)
+    case $ac_sys_system in	
+      Darwin*)
+        PGO_PROF_GEN_FLAG="-fprofile-instr-generate"
+        PGO_PROF_USE_FLAG="-fprofile-instr-use=code.profclangd"
+        LLVM_PROF_MERGER="llvm-profdata merge -output=code.profclangd *.profclangr"
+        LLVM_PROF_FILE="LLVM_PROFILE_FILE=\"code-%p.profclangr\""
+        ;;
+      *)
+        PGO_PROF_GEN_FLAG="-fprofile-generate"
+        PGO_PROF_USE_FLAG="-fprofile-use -fprofile-correction"
+        LLVM_PROF_MERGER="true"
+        LLVM_PROF_FILE=""
+        ;;
+    esac
+    ;;
+esac
+
+
 # On some compilers, pthreads are available without further options
 # (e.g. MacOS X). On some of these systems, the compiler will not
 # complain if unaccepted options are passed (e.g. gcc on Mac OS X).