diff --git a/tests/support/coverage/sitecustomize.py b/tests/support/coverage/sitecustomize.py
new file mode 100644
index 000000000000..76f7babf5f97
--- /dev/null
+++ b/tests/support/coverage/sitecustomize.py
@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+'''
+Python will always try to import sitecustomize.
+We use that fact to try and support code coverage for sub-processes
+'''
+from __future__ import absolute_import
+try:
+    import coverage
+    coverage.process_startup()
+except ImportError:
+    pass
diff --git a/tox.ini b/tox.ini
index d8beec127523..b4ee8d0b8773 100644
--- a/tox.ini
+++ b/tox.ini
@@ -29,6 +29,12 @@ commands = {envpython} {toxinidir}/tests/runtests.py --tests-logfile={toxinidir}
 commands = pytest --rootdir {toxinidir} --log-file={toxinidir}/artifacts/logs/runtests.log {posargs}
 
 [testenv:runtests-coverage]
+# Add tests/support/coverage to PYTHONPATH in order to get code coverage from subprocesses.
+# Additional, set the COVERAGE_PROCESS_START environment variable so that the coverage library
+# knows it's supposed to track subprocesses.
+setenv =
+  PYTHONPATH={toxinidir}/tests/support/coverage
+  COVERAGE_PROCESS_START={toxinidir}/.coveragerc
 commands_pre =
   - coverage erase
 commands =
@@ -38,6 +44,7 @@ commands_post =
   - coverage xml -o {toxinidir}/artifacts/coverage/coverage.xml
 
 [testenv:pytest-coverage]
+setenv = {[testenv:runtests-coverage]setenv}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands = coverage run -m py.test --rootdir {toxinidir} {posargs}
 commands_post = {[testenv:runtests-coverage]commands_post}
@@ -51,17 +58,20 @@ commands = {[testenv:runtests]commands}
 
 [testenv:py2-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py2-runtests-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py2-pytest-coverage]
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:pytest-coverage]commands}
 commands_pre = {[testenv:pytest-coverage]commands_pre}
 commands_post = {[testenv:pytest-coverage]commands_post}
@@ -75,17 +85,20 @@ commands = {[testenv:runtests]commands}
 
 [testenv:py27-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py27-runtests-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py27-pytest-coverage]
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:pytest-coverage]commands}
 commands_pre = {[testenv:pytest-coverage]commands_pre}
 commands_post = {[testenv:pytest-coverage]commands_post}
@@ -99,17 +112,20 @@ commands = {[testenv:runtests]commands}
 
 [testenv:py3-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py3-runtests-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py3-pytest-coverage]
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:pytest-coverage]commands}
 commands_pre = {[testenv:pytest-coverage]commands_pre}
 commands_post = {[testenv:pytest-coverage]commands_post}
@@ -124,17 +140,20 @@ commands = {[testenv:runtests]commands}
 
 [testenv:py34-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py34-runtests-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py34-pytest-coverage]
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:pytest-coverage]commands}
 commands_pre = {[testenv:pytest-coverage]commands_pre}
 commands_post = {[testenv:pytest-coverage]commands_post}
@@ -149,17 +168,20 @@ commands = {[testenv:runtests]commands}
 
 [testenv:py35-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py35-runtests-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py35-pytest-coverage]
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:pytest-coverage]commands}
 commands_pre = {[testenv:pytest-coverage]commands_pre}
 commands_post = {[testenv:pytest-coverage]commands_post}
@@ -174,17 +196,20 @@ commands = {[testenv:runtests]commands}
 
 [testenv:py36-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py36-runtests-coverage]
 deps = {[testenv:runtests]deps}
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:runtests-coverage]commands}
 commands_pre = {[testenv:runtests-coverage]commands_pre}
 commands_post = {[testenv:runtests-coverage]commands_post}
 
 [testenv:py36-pytest-coverage]
+setenv = {[testenv:runtests-coverage]setenv}
 commands = {[testenv:pytest-coverage]commands}
 commands_pre = {[testenv:pytest-coverage]commands_pre}
 commands_post = {[testenv:pytest-coverage]commands_post}