Index: lib/CodeGen/CGExprScalar.cpp
===================================================================
--- lib/CodeGen/CGExprScalar.cpp
+++ lib/CodeGen/CGExprScalar.cpp
@@ -1411,7 +1411,14 @@
   }
   case CK_AddressSpaceConversion: {
     Value *Src = Visit(const_cast<Expr*>(E));
-    return Builder.CreateAddrSpaceCast(Src, ConvertType(DestTy));
+    llvm::Type *SrcTy = Src->getType();
+    llvm::Type *DstTy = ConvertType(DestTy);
+    // Since target may map different address spaces in AST to the same address
+    // space, an address space conversion may end up as a bitcast.
+    if (SrcTy->getPointerAddressSpace() != DstTy->getPointerAddressSpace())
+      return Builder.CreateAddrSpaceCast(Src, DstTy);
+    else
+      return Builder.CreateBitCast(Src, DstTy);
   }
   case CK_AtomicToNonAtomic:
   case CK_NonAtomicToAtomic:
Index: test/CodeGenOpenCL/2016-04-01-addrcast.cl
===================================================================
--- /dev/null
+++ test/CodeGenOpenCL/2016-04-01-addrcast.cl
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 %s -triple x86_64-unknown-linux-gnu -O0 -cl-std=CL2.0 -emit-llvm -o - | FileCheck %s
+
+// When -ffake-address-space-map is not used, all address space mapped to 0 for x86/x86-64, a bitcast should be generated instead of addrspacecast.
+void foo() {
+  global int *a;
+  generic void *b = a;
+  // CHECK: bitcast 
+  // CHECK-NOT: addrspacecast
+}