3 files changed, 24 insertions, 3 deletions
diff --git a/compiler-rt/CMakeLists.txt b/compiler-rt/CMakeLists.txt
index 8485fe9232d0..c5a7b2478e50 100644
--- a/compiler-rt/CMakeLists.txt
+++ b/compiler-rt/CMakeLists.txt
@@ -3,13 +3,20 @@
 # An important constraint of the build is that it only produces libraries
 # based on the ability of the host toolchain to target various platforms.
 
-cmake_minimum_required(VERSION 3.20.0)
+cmake_minimum_required(VERSION 3.13.4)
 
 # Check if compiler-rt is built as a standalone project.
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR COMPILER_RT_STANDALONE_BUILD)
   project(CompilerRT C CXX ASM)
   set(COMPILER_RT_STANDALONE_BUILD TRUE)
   set_property(GLOBAL PROPERTY USE_FOLDERS ON)
+  if ("${CMAKE_VERSION}" VERSION_LESS "3.20.0")
+    message(WARNING
+      "Your CMake version is ${CMAKE_VERSION}. Starting with LLVM 17.0.0, the "
+      "minimum version of CMake required to build LLVM will become 3.20.0, and "
+      "using an older CMake will become an error. Please upgrade your CMake to "
+      "at least 3.20.0 now to avoid issues in the future!")
+  endif()
 endif()
 
 set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
index c3e22a8f354f..a302306cc302 100644
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -3,7 +3,14 @@
 # architecture-specific code in various subdirectories.
 
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
-  cmake_minimum_required(VERSION 3.20.0)
+  cmake_minimum_required(VERSION 3.13.4)
+  if ("${CMAKE_VERSION}" VERSION_LESS "3.20.0")
+    message(WARNING
+      "Your CMake version is ${CMAKE_VERSION}. Starting with LLVM 17.0.0, the "
+      "minimum version of CMake required to build LLVM will become 3.20.0, and "
+      "using an older CMake will become an error. Please upgrade your CMake to "
+      "at least 3.20.0 now to avoid issues in the future!")
+  endif()
 
   set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
   project(CompilerRTBuiltins C ASM)
diff --git a/compiler-rt/lib/crt/CMakeLists.txt b/compiler-rt/lib/crt/CMakeLists.txt
index 32fd61b1fa11..771652f438f8 100644
--- a/compiler-rt/lib/crt/CMakeLists.txt
+++ b/compiler-rt/lib/crt/CMakeLists.txt
@@ -1,5 +1,12 @@
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
-  cmake_minimum_required(VERSION 3.20.0)
+  cmake_minimum_required(VERSION 3.13.4)
+  if ("${CMAKE_VERSION}" VERSION_LESS "3.20.0")
+    message(WARNING
+      "Your CMake version is ${CMAKE_VERSION}. Starting with LLVM 17.0.0, the "
+      "minimum version of CMake required to build LLVM will become 3.20.0, and "
+      "using an older CMake will become an error. Please upgrade your CMake to "
+      "at least 3.20.0 now to avoid issues in the future!")
+  endif()
 
   set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
   project(CompilerRTCRT C)