Index: cfe/trunk/lib/Sema/SemaOverload.cpp
===================================================================
--- cfe/trunk/lib/Sema/SemaOverload.cpp
+++ cfe/trunk/lib/Sema/SemaOverload.cpp
@@ -9422,17 +9422,19 @@
     const FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext);
     bool ContainsSameSideCandidate =
         llvm::any_of(Candidates, [&](OverloadCandidate *Cand) {
-          return Cand->Function &&
+          // Consider viable function only.
+          return Cand->Viable && Cand->Function &&
                  S.IdentifyCUDAPreference(Caller, Cand->Function) ==
                      Sema::CFP_SameSide;
         });
     if (ContainsSameSideCandidate) {
-      auto IsWrongSideCandidate = [&](OverloadCandidate *Cand) {
-        return Cand->Function &&
-               S.IdentifyCUDAPreference(Caller, Cand->Function) ==
-                   Sema::CFP_WrongSide;
-      };
-      llvm::erase_if(Candidates, IsWrongSideCandidate);
+      // Clear viable flag for WrongSide varible candidates.
+      llvm::for_each(Candidates, [&](OverloadCandidate *Cand) {
+        if (Cand->Viable && Cand->Function &&
+            S.IdentifyCUDAPreference(Caller, Cand->Function) ==
+                Sema::CFP_WrongSide)
+          Cand->Viable = false;
+      });
     }
   }
 
Index: cfe/trunk/test/SemaCUDA/function-overload.cu
===================================================================
--- cfe/trunk/test/SemaCUDA/function-overload.cu
+++ cfe/trunk/test/SemaCUDA/function-overload.cu
@@ -402,3 +402,20 @@
 __device__ void test_device_template_overload() {
   template_overload(1); // OK. Attribute-based overloading picks __device__ variant.
 }
+
+// Two classes with `operator-` defined. One of them is device only.
+struct C1;
+struct C2;
+__device__
+int operator-(const C1 &x, const C1 &y);
+int operator-(const C2 &x, const C2 &y);
+
+template <typename T>
+__host__ __device__ int constexpr_overload(const T &x, const T &y) {
+  return x - y;
+}
+
+// Verify that function overloading doesn't prune candidate wrongly.
+int test_constexpr_overload(C2 &x, C2 &y) {
+  return constexpr_overload(x, y);
+}
Index: cfe/trunk/test/SemaCUDA/implicit-member-target-collision-cxx11.cu
===================================================================
--- cfe/trunk/test/SemaCUDA/implicit-member-target-collision-cxx11.cu
+++ cfe/trunk/test/SemaCUDA/implicit-member-target-collision-cxx11.cu
@@ -74,11 +74,13 @@
 struct C4_with_collision : A4_with_host_copy_ctor, B4_with_device_copy_ctor {
 };
 
-// expected-note@-3 {{copy constructor of 'C4_with_collision' is implicitly deleted because base class 'B4_with_device_copy_ctor' has no copy constructor}}
+// expected-note@-3 {{candidate constructor (the implicit copy constructor) not viable: call to invalid function from __host__ function}}
+// expected-note@-4 {{implicit copy constructor inferred target collision: call to both __host__ and __device__ members}}
+// expected-note@-5 {{candidate constructor (the implicit default constructor) not viable: requires 0 arguments, but 1 was provided}}
 
 void hostfoo4() {
   C4_with_collision c;
-  C4_with_collision c2 = c; // expected-error {{call to implicitly-deleted copy constructor of 'C4_with_collision'}}
+  C4_with_collision c2 = c; // expected-error {{no matching constructor for initialization of 'C4_with_collision'}}
 }
 
 //------------------------------------------------------------------------------