Index: cfe/trunk/lib/Headers/__clang_cuda_cmath.h
===================================================================
--- cfe/trunk/lib/Headers/__clang_cuda_cmath.h
+++ cfe/trunk/lib/Headers/__clang_cuda_cmath.h
@@ -75,7 +75,10 @@
 __DEVICE__ bool isinf(float __x) { return ::__isinff(__x); }
 __DEVICE__ bool isinf(double __x) { return ::__isinf(__x); }
 __DEVICE__ bool isfinite(float __x) { return ::__finitef(__x); }
-__DEVICE__ bool isfinite(double __x) { return ::__finite(__x); }
+// For inscrutable reasons, __finite(), the double-precision version of
+// __finitef, does not exist when compiling for MacOS.  __isfinited is available
+// everywhere and is just as good.
+__DEVICE__ bool isfinite(double __x) { return ::__isfinited(__x); }
 __DEVICE__ bool isgreater(float __x, float __y) {
   return __builtin_isgreater(__x, __y);
 }
@@ -141,7 +144,7 @@
   return ::powi(__base, __iexp);
 }
 __DEVICE__ bool signbit(float __x) { return ::__signbitf(__x); }
-__DEVICE__ bool signbit(double __x) { return ::__signbit(__x); }
+__DEVICE__ bool signbit(double __x) { return ::__signbitd(__x); }
 __DEVICE__ float sin(float __x) { return ::sinf(__x); }
 __DEVICE__ float sinh(float __x) { return ::sinhf(__x); }
 __DEVICE__ float sqrt(float __x) { return ::sqrtf(__x); }
Index: cfe/trunk/lib/Headers/__clang_cuda_runtime_wrapper.h
===================================================================
--- cfe/trunk/lib/Headers/__clang_cuda_runtime_wrapper.h
+++ cfe/trunk/lib/Headers/__clang_cuda_runtime_wrapper.h
@@ -121,6 +121,15 @@
 #undef __cxa_vec_delete3
 #undef __cxa_pure_virtual
 
+// math_functions.hpp expects this host function be defined on MacOS, but it
+// ends up not being there because of the games we play here.  Just define it
+// ourselves; it's simple enough.
+#ifdef __APPLE__
+inline __host__ double __signbitd(double x) {
+  return std::signbit(x);
+}
+#endif
+
 // We need decls for functions in CUDA's libdevice with __device__
 // attribute only. Alas they come either as __host__ __device__ or
 // with no attributes at all. To work around that, define __CUDA_RTC__