diff -ur Python-2.7.16.orig/Lib/distutils/ccompiler.py Python-2.7.16/Lib/distutils/ccompiler.py
--- Python-2.7.16.orig/Lib/distutils/ccompiler.py	2019-03-02 19:17:42.000000000 +0100
+++ Python-2.7.16/Lib/distutils/ccompiler.py	2019-03-09 16:30:09.036803900 +0100
@@ -14,7 +14,7 @@
 from distutils.spawn import spawn
 from distutils.file_util import move_file
 from distutils.dir_util import mkpath
-from distutils.dep_util import newer_group
+from distutils.dep_util import newer_group, newer
 from distutils.util import split_quoted, execute
 from distutils import log
 # following import is for backward compatibility
@@ -571,7 +571,9 @@
                 src, ext = build[obj]
             except KeyError:
                 continue
-            self._compile(obj, src, ext, cc_args, extra_postargs, pp_opts)
+            if newer(src, obj):
+                # some extensions share source files so we need to avoid compiling the same source multiple times
+                self._compile(obj, src, ext, cc_args, extra_postargs, pp_opts)
 
         # Return *all* object filenames, not just the ones we just built.
         return objects
diff -ur Python-2.7.16.orig/Lib/distutils/dep_util.py Python-2.7.16/Lib/distutils/dep_util.py
--- Python-2.7.16.orig/Lib/distutils/dep_util.py	2019-03-02 19:17:42.000000000 +0100
+++ Python-2.7.16/Lib/distutils/dep_util.py	2019-03-09 16:30:09.036803900 +0100
@@ -11,7 +11,7 @@
 from distutils.errors import DistutilsFileError
 
 def newer(source, target):
-    """Tells if the target is newer than the source.
+    """Tells if the source is newer than the target.
 
     Return true if 'source' exists and is more recently modified than
     'target', or if 'source' exists and 'target' doesn't.
diff -ur Python-2.7.16.orig/Makefile.pre.in Python-2.7.16/Makefile.pre.in
--- Python-2.7.16.orig/Makefile.pre.in	2019-03-09 16:29:29.004188933 +0100
+++ Python-2.7.16/Makefile.pre.in	2019-03-09 16:33:30.788823762 +0100
@@ -209,9 +209,9 @@
 TCLTK_LIBS=	@TCLTK_LIBS@
 
 # The task to run while instrument when building the profile-opt target
-# We exclude unittests with -x that take a rediculious amount of time to
-# run in the instrumented training build or do not provide much value.
-PROFILE_TASK=-m test.regrtest --pgo -x test_asyncore test_gdb test_multiprocessing test_subprocess
+# We exclude unittests with -x that take a ridiculous amount of time to
+# run in the instrumented training build or do not provide much value
+PROFILE_TASK=-m test.regrtest --pgo $(EXTRATESTOPTS) -x test_asyncore test_gdb test_multiprocessing test_subprocess test_xpickle
 
 # report files for gcov / lcov coverage report
 COVERAGE_INFO=	$(abs_builddir)/coverage.info
@@ -437,7 +437,7 @@
 
 run_profile_task:
 	: # FIXME: can't run for a cross build
-	$(LLVM_PROF_FILE) $(RUNSHARED) ./$(BUILDPYTHON) $(PROFILE_TASK) || true
+	$(LLVM_PROF_FILE) _PYTHONNOSITEPACKAGES=1 $(RUNSHARED) ./$(BUILDPYTHON) -E $(PROFILE_TASK) || true # allow failures here
 
 build_all_merge_profile:
 	$(LLVM_PROF_MERGER)
diff -ur Python-2.7.16.orig/setup.py Python-2.7.16/setup.py
--- Python-2.7.16.orig/setup.py	2019-03-09 16:29:29.028188103 +0100
+++ Python-2.7.16/setup.py	2019-03-09 16:30:09.037803866 +0100
@@ -269,11 +269,13 @@
         # those environment variables passed into the setup.py phase.  Here's
         # a small set of useful ones.
         compiler = os.environ.get('CC')
+        # it's important to get CFLAGS from the environment for proper extension PGO support
+        cflags = os.environ.get('CFLAGS', sysconfig.get_config_vars('CFLAGS')[0])
         args = {}
         # unfortunately, distutils doesn't let us provide separate C and C++
         # compilers
         if compiler is not None:
-            (ccshared,cflags) = sysconfig.get_config_vars('CCSHARED','CFLAGS')
+            (ccshared,) = sysconfig.get_config_vars('CCSHARED')
             args['compiler_so'] = compiler + ' ' + ccshared + ' ' + cflags
         self.compiler.set_executables(**args)