diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 80cf3866ab8..2608365e58b 100644
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -12,6 +12,14 @@
 //
 //===----------------------------------------------------------------------===//
 
+// Force NDEBUG on in any optimized build on Darwin.
+//
+// FIXME: This is a huge hack, to work around ridiculously awful compile times
+// on this file with gcc-4.2 on Darwin, in Release mode.
+#if defined(__APPLE__) && defined(__OPTIMIZE__) && !defined(NDEBUG)
+#define NDEBUG
+#endif
+
 #define DEBUG_TYPE "x86-isel"
 #include "X86.h"
 #include "X86InstrBuilder.h"