diff --git a/third_party/toolchains/preconfig/ubuntu16.04/py3_opt/BUILD b/third_party/toolchains/preconfig/ubuntu16.04/py3_opt/BUILD
index 689465253b8..6a5e02d7b2a 100755
--- a/third_party/toolchains/preconfig/ubuntu16.04/py3_opt/BUILD
+++ b/third_party/toolchains/preconfig/ubuntu16.04/py3_opt/BUILD
@@ -2,6 +2,34 @@ licenses(["restricted"])
 
 package(default_visibility = ["//visibility:public"])
 
+# Point both runtimes to the same python binary to ensure we always
+# use the python binary specified by ./configure.py script.
+load("@bazel_tools//tools/python:toolchain.bzl", "py_runtime_pair")
+
+py_runtime(
+    name = "py2_runtime",
+    interpreter_path = "/usr/bin/python2",
+    python_version = "PY2",
+)
+
+py_runtime(
+    name = "py3_runtime",
+    interpreter_path = "/usr/bin/python2",
+    python_version = "PY3",
+)
+
+py_runtime_pair(
+    name = "py_runtime_pair",
+    py2_runtime = ":py2_runtime",
+    py3_runtime = ":py3_runtime",
+)
+
+toolchain(
+    name = "py_toolchain",
+    toolchain = ":py_runtime_pair",
+    toolchain_type = "@bazel_tools//tools/python:toolchain_type",
+)
+
 # To build Python C/C++ extension on Windows, we need to link to python import library pythonXY.lib
 # See https://docs.python.org/3/extending/windows.html
 cc_import(