diff --git a/news/5499.feature b/news/5499.feature
new file mode 100644
index 00000000000..8f5d4773126
--- /dev/null
+++ b/news/5499.feature
@@ -0,0 +1 @@
+Report to Warehouse that pip is running under CI if the ``PIP_IS_CI`` environment variable is set.
diff --git a/src/pip/_internal/download.py b/src/pip/_internal/download.py
index 8b3b7a8775c..0dd22dd1e53 100644
--- a/src/pip/_internal/download.py
+++ b/src/pip/_internal/download.py
@@ -95,6 +95,8 @@
     'BUILD_ID',
     # AppVeyor, CircleCI, Codeship, Gitlab CI, Shippable, Travis CI
     'CI',
+    # Explicit environment variable.
+    'PIP_IS_CI',
 )
 
 
diff --git a/tests/unit/test_download.py b/tests/unit/test_download.py
index 57f3cdeb5fa..de86fcf03c0 100644
--- a/tests/unit/test_download.py
+++ b/tests/unit/test_download.py
@@ -73,6 +73,7 @@ def test_user_agent():
     ('BUILD_BUILDID', True),
     ('BUILD_ID', True),
     ('CI', True),
+    ('PIP_IS_CI', True),
     # Test a prefix substring of one of the variable names we use.
     ('BUILD', False),
 ])