Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -135,6 +135,7 @@
 # about #include_next which is used everywhere.
 option(LIBCXX_ENABLE_PEDANTIC "Compile with pedantic enabled." OFF)
 option(LIBCXX_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
+option(LIBCXX_DISABLE_DEALLOCATE_MACRO_WARNING "Disable __deallocate macro #warning." OFF)
 
 option(LIBCXX_GENERATE_COVERAGE "Enable generating code coverage." OFF)
 set(LIBCXX_COVERAGE_LIBRARY "" CACHE STRING
@@ -323,6 +324,9 @@
 if (LIBCXX_ENABLE_PEDANTIC)
   add_compile_flags_if_supported(-pedantic)
 endif()
+if (LIBCXX_DISABLE_DEALLOCATE_MACRO_WARNING)
+  add_definitions(-D_LIBCPP_DISABLE_DEALLOCATE_MACRO_WARNING)
+endif()
 
 # Exception flags =============================================================
 if (LIBCXX_ENABLE_EXCEPTIONS)
Index: include/__undef___deallocate
===================================================================
--- include/__undef___deallocate
+++ include/__undef___deallocate
@@ -12,7 +12,9 @@
 #if defined(_MSC_VER) && !defined(__clang__)
 _LIBCPP_WARNING("macro __deallocate is incompatible with C++.  #undefining __deallocate")
 #else
+#if !defined(_LIBCPP_DISABLE_DEALLOCATE_MACRO_WARNING)
 #warning: macro __deallocate is incompatible with C++.  #undefining __deallocate
 #endif
+#endif
 #undef __deallocate
 #endif