Index: llvm/utils/gn/build/BUILD.gn
===================================================================
--- llvm/utils/gn/build/BUILD.gn
+++ llvm/utils/gn/build/BUILD.gn
@@ -5,11 +5,6 @@
 config("compiler_defaults") {
   defines = []
 
-  # FIXME: Don't define this globally here.
-  if (host_os != "win") {
-    defines += [ "LLVM_ON_UNIX" ]
-  }
-
   if (!llvm_enable_assertions) {
     defines += [ "NDEBUG" ]
   }