diff --git a/Lib/test/libregrtest/setup.py b/Lib/test/libregrtest/setup.py
index 9a6585af9d0dd6..ebaac26bc75ef1 100644
--- a/Lib/test/libregrtest/setup.py
+++ b/Lib/test/libregrtest/setup.py
@@ -72,7 +72,10 @@ def setup_tests(ns):
         else:
             soft, hard = resource.getrlimit(resource.RLIMIT_STACK)
             newsoft = min(hard, max(soft, 1024*2048))
-            resource.setrlimit(resource.RLIMIT_STACK, (newsoft, hard))
+            try:
+                resource.setrlimit(resource.RLIMIT_STACK, (newsoft, hard))
+            except ValueError:
+                pass
 
     if ns.huntrleaks:
         unittest.BaseTestSuite._cleanup = False
diff --git a/Misc/NEWS.d/next/macOS/2019-04-14-10-22-55.bpo-36231._BPeg4.rst b/Misc/NEWS.d/next/macOS/2019-04-14-10-22-55.bpo-36231._BPeg4.rst
new file mode 100644
index 00000000000000..5fed01e4424952
--- /dev/null
+++ b/Misc/NEWS.d/next/macOS/2019-04-14-10-22-55.bpo-36231._BPeg4.rst
@@ -0,0 +1 @@
+On macOS 10.14, Xcode comes without /usr/include. We allow MacOS build to use headers from Xcode, without an /usr/include present.
\ No newline at end of file
diff --git a/configure b/configure
index 9c7eded8535985..4707828e1818fd 100755
--- a/configure
+++ b/configure
@@ -7354,6 +7354,11 @@ $as_echo "$ac_cv_enable_implicit_function_declaration_error" >&6; }
     Darwin*)
         # -Wno-long-double, -no-cpp-precomp, and -mno-fused-madd
         # used to be here, but non-Apple gcc doesn't accept them.
+
+cat >>confdefs.h <<_ACEOF
+#define Py_MACOS_SYSROOT `xcrun --show-sdk-path`
+_ACEOF
+
         if test "${CC}" = gcc
         then
             { $as_echo "$as_me:${as_lineno-$LINENO}: checking which compiler should be used" >&5
diff --git a/configure.ac b/configure.ac
index 6450519444c8d3..1720944534688c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1802,6 +1802,7 @@ yes)
     Darwin*)
         # -Wno-long-double, -no-cpp-precomp, and -mno-fused-madd
         # used to be here, but non-Apple gcc doesn't accept them.
+        AC_DEFINE_UNQUOTED([Py_MACOS_SYSROOT], [`xcrun --show-sdk-path`], [Get the root dir of XCode])
         if test "${CC}" = gcc
         then
             AC_MSG_CHECKING(which compiler should be used)
diff --git a/pyconfig.h.in b/pyconfig.h.in
index d41d57932766be..381d5c014c957b 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -1374,6 +1374,9 @@
    externally defined: 0 */
 #undef Py_HASH_ALGORITHM
 
+/* Get the root dir of XCode */
+#undef Py_MACOS_SYSROOT
+
 /* assume C89 semantics that RETSIGTYPE is always void */
 #undef RETSIGTYPE
 
diff --git a/setup.py b/setup.py
index 30caed5b51c1ea..954752653d34e2 100644
--- a/setup.py
+++ b/setup.py
@@ -134,7 +134,7 @@ def macosx_sdk_root():
     cflags = sysconfig.get_config_var('CFLAGS')
     m = re.search(r'-isysroot\s+(\S+)', cflags)
     if m is None:
-        sysroot = '/'
+        sysroot = sysconfig.get_config_var('Py_MACOS_SYSROOT')
     else:
         sysroot = m.group(1)
     return sysroot
@@ -669,6 +669,7 @@ def init_inc_lib_dirs(self):
             # NOTE: using shlex.split would technically be more correct, but
             # also gives a bootstrap problem. Let's hope nobody uses
             # directories with whitespace in the name to store libraries.
+            self.inc_dirs.append('/usr/include')
             cflags, ldflags = sysconfig.get_config_vars(
                     'CFLAGS', 'LDFLAGS')
             for item in cflags.split():