Index: mlir/lib/ExecutionEngine/AsyncRuntime.cpp
===================================================================
--- mlir/lib/ExecutionEngine/AsyncRuntime.cpp
+++ mlir/lib/ExecutionEngine/AsyncRuntime.cpp
@@ -24,8 +24,6 @@
 #include <thread>
 #include <vector>
 
-using namespace mlir::runtime;
-
 //===----------------------------------------------------------------------===//
 // Async runtime API.
 //===----------------------------------------------------------------------===//
@@ -167,8 +165,11 @@
   std::vector<std::function<void()>> awaiters;
 };
 
-} // namespace runtime
-} // namespace mlir
+//===----------------------------------------------------------------------===//
+// These extern "C" functions have their prototypes declared in C++
+// namespace, to have them properly exported by MSVC, they need to be inside the
+// same namespace or be qualified with the namespace.
+//===----------------------------------------------------------------------===//
 
 // Adds references to reference counted runtime object.
 extern "C" void mlirAsyncRuntimeAddRef(RefCountedObjPtr ptr, int32_t count) {
@@ -342,4 +343,7 @@
   std::cout << "Current thread id: " << thisId << std::endl;
 }
 
+} // namespace runtime
+} // namespace mlir
+
 #endif // MLIR_ASYNCRUNTIME_DEFINE_FUNCTIONS