diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -1,5 +1,11 @@
 cmake_minimum_required(VERSION 3.13.4)
 
+# Maintain old behavior of transforming DEPFILEs to Ninja for TableGen with
+# cmake 3.20 or above.
+if (POLICY CMP0116)
+  cmake_policy(SET CMP0116 OLD)
+endif()
+
 # Default to C++17
 set(CMAKE_CXX_STANDARD 17)