diff -r b74897b69184 Doc/library/sys.rst
--- a/Doc/library/sys.rst	Wed Nov 02 20:33:07 2016 -0400
+++ b/Doc/library/sys.rst	Thu Nov 03 10:18:12 2016 +0900
@@ -244,6 +244,9 @@
    the real path to its executable, :data:`sys.executable` will be an empty string
    or ``None``.
 
+   .. versionchanged:: 3.7
+      Included executable suffix to path, if platform has it.
+
 
 .. function:: exit([arg])
 
diff -r b74897b69184 Makefile.pre.in
--- a/Makefile.pre.in	Wed Nov 02 20:33:07 2016 -0400
+++ b/Makefile.pre.in	Thu Nov 03 10:18:12 2016 +0900
@@ -751,6 +751,7 @@
 		-DEXEC_PREFIX='"$(exec_prefix)"' \
 		-DVERSION='"$(VERSION)"' \
 		-DVPATH='"$(VPATH)"' \
+		-DEXE_SUFFIX='"$(EXE)"' \
 		-o $@ $(srcdir)/Modules/getpath.c
 
 Programs/python.o: $(srcdir)/Programs/python.c
diff -r b74897b69184 Modules/getpath.c
--- a/Modules/getpath.c	Wed Nov 02 20:33:07 2016 -0400
+++ b/Modules/getpath.c	Thu Nov 03 10:18:12 2016 +0900
@@ -101,8 +101,9 @@
 #endif
 
 
-#if !defined(PREFIX) || !defined(EXEC_PREFIX) || !defined(VERSION) || !defined(VPATH)
-#error "PREFIX, EXEC_PREFIX, VERSION, and VPATH must be constant defined"
+#if !defined(PREFIX) || !defined(EXEC_PREFIX) || !defined(VERSION) || \
+    !defined(VPATH) || !defined(EXE_SUFFIX)
+#error "PREFIX, EXEC_PREFIX, VERSION, VPATH, and EXE_SUFFIX must be constant defined"
 #endif
 
 #ifndef LANDMARK
@@ -254,6 +255,36 @@
     wcscpy(path, buffer);
 }
 
+
+/* add_exe_suffix requires that progpath be allocated at least
+   MAXPATHLEN + 1 bytes.
+*/
+static void
+add_exe_suffix(wchar_t *progpath)
+{
+    wchar_t *_suffix;
+    size_t n, k;
+
+    _suffix = Py_DecodeLocale(EXE_SUFFIX, NULL);
+    if (_suffix == NULL) {
+        Py_FatalError("Unable to decode suffix variables in getpath.c: "
+                      "memory error");
+    }
+
+    n = wcslen(progpath);
+    k = wcslen(_suffix);
+    /* Check for already have an executable suffix */
+    if (wcsncasecmp(_suffix, progpath+n-k, k) != 0) {
+        if (n + k > MAXPATHLEN) {
+            Py_FatalError("progpath overflow in getpath.c's add_exe_suffix()");
+        }
+        wcsncpy(progpath+n, _suffix, k);
+        progpath[n+k] = '\0';
+    }
+    PyMem_RawFree(_suffix);
+}
+
+
 /* search for a prefix value in an environment file. If found, copy it
    to the provided buffer, which is expected to be no more than MAXPATHLEN
    bytes long.
@@ -563,6 +594,10 @@
     PyMem_RawFree(path_buffer);
     if (progpath[0] != SEP && progpath[0] != '\0')
         absolutize(progpath);
+
+    if (EXE_SUFFIX[0] != '\0' && progpath[0] != '\0')
+        add_exe_suffix(progpath);
+
     wcsncpy(argv0_path, progpath, MAXPATHLEN);
     argv0_path[MAXPATHLEN] = '\0';