diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 6df818c..9ac4ce8 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -193,6 +193,10 @@
   if (!sentinelExpr) return;
   if (sentinelExpr->isTypeDependent()) return;
   if (sentinelExpr->isValueDependent()) return;
+
+  // nullptr_t is always treated as null.
+  if (sentinelExpr->getType()->isNullPtrType()) return;
+
   if (sentinelExpr->getType()->isAnyPointerType() &&
       sentinelExpr->IgnoreParenCasts()->isNullPointerConstant(Context,
                                             Expr::NPC_ValueDependentIsNull))
diff --git a/test/SemaCXX/nullptr.cpp b/test/SemaCXX/nullptr.cpp
index 0a0d098..4f6e2e6 100644
--- a/test/SemaCXX/nullptr.cpp
+++ b/test/SemaCXX/nullptr.cpp
@@ -84,3 +84,12 @@
 // Test that we prefer g(void*) over g(bool).
 static_assert(is_same<decltype(g(nullptr)), void*>::value, "");
 }
+
+namespace test2 {
+  void f(int, ...) __attribute__((sentinel));
+
+  void g() {
+    // nullptr can be used as the sentinel value.
+    f(10, nullptr);
+  }
+}