diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6509d4adeef..8f9c8ad7418 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -48,7 +48,9 @@ include(tools/cmake/Utils.cmake)
 include(CMakeDependentOption)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
-
+# Set a flag to override the compatiblity error caused by CMake 4.0.0+ dropping support for
+# things like `cmake_minimum_required (VERSION 3.0.2 FATAL_ERROR)`
+set(CMAKE_POLICY_VERSION_MINIMUM 3.5)
 if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
diff --git a/install_requirements.py b/install_requirements.py
index 4b3de68b8db..0a950e91f31 100644
--- a/install_requirements.py
+++ b/install_requirements.py
@@ -123,6 +123,9 @@ def install_requirements(use_pytorch_nightly):
     # This is usually not recommended.
     new_env = os.environ.copy()
     new_env["USE_CPP"] = "1"  # install torchao kernels
+    # Set a flag to override the compatiblity error caused by CMake 4.0.0+ dropping support for
+    # things like `cmake_minimum_required (VERSION 3.0.2 FATAL_ERROR)`
+    new_env["CMAKE_POLICY_VERSION_MINIMUM"] = "3.5"
     subprocess.run(
         [
             sys.executable,
diff --git a/setup.py b/setup.py
index 871fdf329c2..49fd267f183 100644
--- a/setup.py
+++ b/setup.py
@@ -709,6 +709,9 @@ def run(self):
             "-DEXECUTORCH_ENABLE_LOGGING=ON",
             "-DEXECUTORCH_LOG_LEVEL=Info",
             "-DCMAKE_OSX_DEPLOYMENT_TARGET=10.15",
+            # Set a flag to override the compatiblity error caused by CMake 4.0.0+ dropping support for
+            # things like `cmake_minimum_required (VERSION 3.0.2 FATAL_ERROR)`
+            "-DCMAKE_POLICY_VERSION_MINIMUM=3.5",
             # The separate host project is only required when cross-compiling,
             # and it can cause build race conditions (libflatcc.a errors) when
             # enabled. TODO(dbort): Remove this override once this option is