diff --git a/compiler-rt/CMakeLists.txt b/compiler-rt/CMakeLists.txt
index deb6994f48185..1c24b520da985 100644
--- a/compiler-rt/CMakeLists.txt
+++ b/compiler-rt/CMakeLists.txt
@@ -12,6 +12,11 @@ endif()
 include(${LLVM_COMMON_CMAKE_UTILS}/Modules/CMakePolicy.cmake
   NO_POLICY_SCOPE)
 
+# TODO(CMake 3.22): remove
+if(POLICY CMP0128)
+  cmake_policy(SET CMP0128 NEW)
+endif()
+
 # 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)
diff --git a/compiler-rt/cmake/Modules/AddCompilerRT.cmake b/compiler-rt/cmake/Modules/AddCompilerRT.cmake
index 6962b733733a6..e3d81d241b105 100644
--- a/compiler-rt/cmake/Modules/AddCompilerRT.cmake
+++ b/compiler-rt/cmake/Modules/AddCompilerRT.cmake
@@ -161,7 +161,8 @@ endmacro()
 #                         LINK_LIBS <linked libraries> (only for shared library)
 #                         OBJECT_LIBS <object libraries to use as sources>
 #                         PARENT_TARGET <convenience parent target>
-#                         ADDITIONAL_HEADERS <header files>)
+#                         ADDITIONAL_HEADERS <header files>
+#                         EXTENSIONS <boolean>)
 function(add_compiler_rt_runtime name type)
   if(NOT type MATCHES "^(OBJECT|STATIC|SHARED|MODULE)$")
     message(FATAL_ERROR
@@ -171,7 +172,7 @@ function(add_compiler_rt_runtime name type)
   cmake_parse_arguments(LIB
     ""
     "PARENT_TARGET"
-    "OS;ARCHS;SOURCES;CFLAGS;LINK_FLAGS;DEFS;DEPS;LINK_LIBS;OBJECT_LIBS;ADDITIONAL_HEADERS"
+    "OS;ARCHS;SOURCES;CFLAGS;LINK_FLAGS;DEFS;DEPS;LINK_LIBS;OBJECT_LIBS;ADDITIONAL_HEADERS;EXTENSIONS"
     ${ARGN})
   set(libnames)
   # Until we support this some other way, build compiler-rt runtime without LTO
@@ -435,6 +436,10 @@ function(add_compiler_rt_runtime name type)
     if(type STREQUAL "SHARED")
       rt_externalize_debuginfo(${libname})
     endif()
+
+    if(DEFINED LIB_EXTENSIONS)
+      set_target_properties(${libname} PROPERTIES C_EXTENSIONS ${LIB_EXTENSIONS})
+    endif()
   endforeach()
   if(LIB_PARENT_TARGET)
     add_dependencies(${LIB_PARENT_TARGET} ${libnames})
diff --git a/compiler-rt/lib/profile/CMakeLists.txt b/compiler-rt/lib/profile/CMakeLists.txt
index ef23492514898..2617841296720 100644
--- a/compiler-rt/lib/profile/CMakeLists.txt
+++ b/compiler-rt/lib/profile/CMakeLists.txt
@@ -138,7 +138,8 @@ if(APPLE)
     CFLAGS ${EXTRA_FLAGS}
     SOURCES ${PROFILE_SOURCES}
     ADDITIONAL_HEADERS ${PROFILE_HEADERS}
-    PARENT_TARGET profile)
+    PARENT_TARGET profile
+    EXTENSIONS ON)
 else()
   add_compiler_rt_runtime(clang_rt.profile
     STATIC
@@ -146,5 +147,6 @@ else()
     CFLAGS ${EXTRA_FLAGS}
     SOURCES ${PROFILE_SOURCES}
     ADDITIONAL_HEADERS ${PROFILE_HEADERS}
-    PARENT_TARGET profile)
+    PARENT_TARGET profile
+    EXTENSIONS ON)
 endif()