Index: llvm/utils/TableGen/CMakeLists.txt
--- llvm/utils/TableGen/CMakeLists.txt.orig
+++ llvm/utils/TableGen/CMakeLists.txt
@@ -81,3 +81,5 @@ add_tablegen(llvm-tblgen LLVM
   DEPENDS
   intrinsics_gen # via llvm-min-tablegen
   )
+
+add_definitions(-D_LIBCPP_USE_LOWER_DEQUE_BLOCK_SIZE)
