Index: lib/Target/Mips/MipsISelLowering.h
===================================================================
--- lib/Target/Mips/MipsISelLowering.h
+++ lib/Target/Mips/MipsISelLowering.h
@@ -269,6 +269,14 @@
     unsigned getRegisterByName(const char* RegName, EVT VT,
                                SelectionDAG &DAG) const override;
 
+    /// Returns true if a cast between SrcAS and DestAS is a noop.
+    bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const override {
+      // Mips doesn't have any special address spaces so we just reserve
+      // the first 256 for software use (e.g. OpenCL) and treat casts
+      // between them as noops.
+      return SrcAS < 256 && DestAS < 256;
+    }
+
   protected:
     SDValue getGlobalReg(SelectionDAG &DAG, EVT Ty) const;
 
Index: test/CodeGen/Mips/llvm-ir/addrspacecast.ll
===================================================================
--- /dev/null
+++ test/CodeGen/Mips/llvm-ir/addrspacecast.ll
@@ -0,0 +1,12 @@
+; RUN: llc < %s -march=mips -mcpu=mips2 | FileCheck %s -check-prefix=ALL
+
+; Address spaces 1-255 are software defined.
+define i32* @cast(i32 *%arg) {
+  %1 = addrspacecast i32* %arg to i32 addrspace(1)*
+  %2 = addrspacecast i32 addrspace(1)* %1 to i32 addrspace(2)*
+  %3 = addrspacecast i32 addrspace(2)* %2 to i32 addrspace(0)*
+  ret i32* %3
+}
+
+; ALL-LABEL: cast:
+; ALL:           move   $2, $4