diff --git a/Lib/test/libregrtest/cmdline.py b/Lib/test/libregrtest/cmdline.py
index 9f1bf6800824a6..c8fedc7ad329bd 100644
--- a/Lib/test/libregrtest/cmdline.py
+++ b/Lib/test/libregrtest/cmdline.py
@@ -264,7 +264,9 @@ def _create_parser():
                        help='only write the name of test cases that will be run'
                             ' , don\'t execute them')
     group.add_argument('-P', '--pgo', dest='pgo', action='store_true',
-                       help='enable Profile Guided Optimization training')
+                       help='enable Profile Guided Optimization (PGO) training')
+    group.add_argument('--pgo-extended', action='store_true',
+                       help='enable extended PGO training (slower training)')
     group.add_argument('--fail-env-changed', action='store_true',
                        help='if a test file alters the environment, mark '
                             'the test as failed')
@@ -344,6 +346,8 @@ def _parse_args(args, **kwargs):
         parser.error("-G/--failfast needs either -v or -W")
     if ns.pgo and (ns.verbose or ns.verbose2 or ns.verbose3):
         parser.error("--pgo/-v don't go together!")
+    if ns.pgo_extended:
+        ns.pgo = True  # pgo_extended implies pgo
 
     if ns.nowindows:
         print("Warning: the --nowindows (-n) option is deprecated. "
diff --git a/Lib/test/libregrtest/main.py b/Lib/test/libregrtest/main.py
index e2274254fdb89c..78b6790685c9df 100644
--- a/Lib/test/libregrtest/main.py
+++ b/Lib/test/libregrtest/main.py
@@ -17,6 +17,7 @@
     INTERRUPTED, CHILD_ERROR, TEST_DID_NOT_RUN,
     PROGRESS_MIN_TIME, format_test_result, is_failed)
 from test.libregrtest.setup import setup_tests
+from test.libregrtest.pgo import setup_pgo_tests
 from test.libregrtest.utils import removepy, count, format_duration, printlist
 from test import support
 
@@ -214,6 +215,9 @@ def find_tests(self, tests):
 
         removepy(self.tests)
 
+        # add default PGO tests if no tests are specified
+        setup_pgo_tests(self.ns)
+
         stdtests = STDTESTS[:]
         nottests = NOTTESTS.copy()
         if self.ns.exclude:
diff --git a/Lib/test/libregrtest/pgo.py b/Lib/test/libregrtest/pgo.py
new file mode 100644
index 00000000000000..327f19374c3ff0
--- /dev/null
+++ b/Lib/test/libregrtest/pgo.py
@@ -0,0 +1,52 @@
+# Set of tests run by default if --pgo is specified.  The tests below were
+# chosen based on the following criteria: either they exercise a commonly used
+# C extension module or type, or they run some relatively typical Python code.
+# Long running tests should be avoided because the PGO instrumented executable
+# runs slowly.
+PGO_TESTS = [
+    'test_array',
+    'test_base64',
+    'test_binascii',
+    'test_binop',
+    'test_bisect',
+    'test_bytes',
+    'test_cmath',
+    'test_codecs',
+    'test_collections',
+    'test_complex',
+    'test_dataclasses',
+    'test_datetime',
+    'test_decimal',
+    'test_difflib',
+    'test_embed',
+    'test_float',
+    'test_fstring',
+    'test_functools',
+    'test_generators',
+    'test_hashlib',
+    'test_heapq',
+    'test_int',
+    'test_itertools',
+    'test_json',
+    'test_long',
+    'test_math',
+    'test_memoryview',
+    'test_operator',
+    'test_ordered_dict',
+    'test_pickle',
+    'test_pprint',
+    'test_re',
+    'test_set',
+    'test_statistics',
+    'test_struct',
+    'test_tabnanny',
+    'test_time',
+    'test_unicode',
+    'test_xml_etree',
+    'test_xml_etree_c',
+]
+
+def setup_pgo_tests(ns):
+    if not ns.args and not ns.pgo_extended:
+        # run default set of tests for PGO training
+        ns.args = PGO_TESTS[:]
diff --git a/Makefile.pre.in b/Makefile.pre.in
index ef9a4f88598f13..318756fd5b9c32 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -255,9 +255,10 @@ TCLTK_INCLUDES=	@TCLTK_INCLUDES@
 TCLTK_LIBS=	@TCLTK_LIBS@
 
 # The task to run while instrumented 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
+# To speed up profile generation, we don't run the full unit test suite
+# by default. The default is "-m test --pgo". To run more tests, use
+# PROFILE_TASK="-m test --pgo-extended"
+PROFILE_TASK=	@PROFILE_TASK@
 
 # report files for gcov / lcov coverage report
 COVERAGE_INFO=	$(abs_builddir)/coverage.info
diff --git a/Misc/NEWS.d/next/Build/2019-07-11-01-28-24.bpo-36044.gIgfiJ.rst b/Misc/NEWS.d/next/Build/2019-07-11-01-28-24.bpo-36044.gIgfiJ.rst
new file mode 100644
index 00000000000000..177c4cb6d17c77
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2019-07-11-01-28-24.bpo-36044.gIgfiJ.rst
@@ -0,0 +1,9 @@
+Reduce the number of unit tests run for the PGO generation task.  This
+speeds up the task by a factor of about 15x.  Running the full unit test
+suite is slow.  This change may result in a slightly less optimized build
+since not as many code branches will be executed.  If you are willing to
+wait for the much slower build, the old behavior can be restored using
+'./configure [..] PROFILE_TASK="-m test --pgo-extended"'.  We make no
+guarantees as to which PGO task set produces a faster build.  Users who
+care should run their own relevant benchmarks as results can depend on
+the environment, workload, and compiler tool chain.
diff --git a/configure b/configure
index 2c49d853a384a0..4cea98e3652896 100755
--- a/configure
+++ b/configure
@@ -686,6 +686,7 @@ target_vendor
 target_cpu
 target
 LLVM_AR
+PROFILE_TASK
 DEF_MAKE_RULE
 DEF_MAKE_ALL_RULE
 ABIFLAGS
@@ -856,6 +857,7 @@ LDFLAGS
 LIBS
 CPPFLAGS
 CPP
+PROFILE_TASK
 PKG_CONFIG
 PKG_CONFIG_PATH
 PKG_CONFIG_LIBDIR'
@@ -1559,6 +1561,8 @@ Some influential environment variables:
   CPPFLAGS    (Objective) C/C++ preprocessor flags, e.g. -I<include dir> if
               you have headers in a nonstandard directory <include dir>
   CPP         C preprocessor
+  PROFILE_TASK
+              Python args for PGO generation task
   PKG_CONFIG  path to pkg-config utility
   PKG_CONFIG_PATH
               directories to add to pkg-config's search path
@@ -6426,6 +6430,16 @@ else
   DEF_MAKE_RULE="all"
 fi
 
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking PROFILE_TASK" >&5
+$as_echo_n "checking PROFILE_TASK... " >&6; }
+if test -z "$PROFILE_TASK"
+then
+	PROFILE_TASK='-m test --pgo'
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $PROFILE_TASK" >&5
+$as_echo "$PROFILE_TASK" >&6; }
+
 # Make llvm-relatec checks work on systems where llvm tools are not installed with their
 # normal names in the default $PATH (ie: Ubuntu).  They exist under the
 # non-suffixed name in their versioned llvm directory.
diff --git a/configure.ac b/configure.ac
index cc31df866d522f..b9759e12f89f74 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1293,6 +1293,14 @@ else
   DEF_MAKE_RULE="all"
 fi
 
+AC_ARG_VAR(PROFILE_TASK, Python args for PGO generation task)
+AC_MSG_CHECKING(PROFILE_TASK)
+if test -z "$PROFILE_TASK"
+then
+	PROFILE_TASK='-m test --pgo'
+fi
+AC_MSG_RESULT($PROFILE_TASK)
+
 # Make llvm-relatec checks work on systems where llvm tools are not installed with their
 # normal names in the default $PATH (ie: Ubuntu).  They exist under the
 # non-suffixed name in their versioned llvm directory.