diff --git a/clang/docs/index.rst b/clang/docs/index.rst
--- a/clang/docs/index.rst
+++ b/clang/docs/index.rst
@@ -109,6 +109,5 @@
 ==================
 
 * :ref:`genindex`
-* :ref:`modindex`
 * :ref:`search`
 
diff --git a/flang/docs/index.md b/flang/docs/index.md
--- a/flang/docs/index.md
+++ b/flang/docs/index.md
@@ -68,6 +68,5 @@
 
 ```eval_rst
 * :ref:`genindex`
-* :ref:`modindex`
 * :ref:`search`
 ```