Index: llvm/lib/IR/Instructions.cpp
===================================================================
--- llvm/lib/IR/Instructions.cpp
+++ llvm/lib/IR/Instructions.cpp
@@ -2891,13 +2891,19 @@
         "Illegal addrspacecast, bitcast sequence!");
       // Allowed, use first cast's opcode
       return firstOp;
-    case 14:
+    case 14: {
       // bitcast, addrspacecast -> addrspacecast if the element type of
       // bitcast's source is the same as that of addrspacecast's destination.
-      if (SrcTy->getScalarType()->getPointerElementType() ==
-          DstTy->getScalarType()->getPointerElementType())
+      PointerType *SrcPtrTy = cast<PointerType>(SrcTy->getScalarType());
+      PointerType *DstPtrTy = cast<PointerType>(DstTy->getScalarType());
+      Type *SrcElemTy =
+          !SrcPtrTy->isOpaque() ? SrcPtrTy->getElementType() : nullptr;
+      Type *DstElemTy =
+          !DstPtrTy->isOpaque() ? DstPtrTy->getElementType() : nullptr;
+      if (SrcElemTy == DstElemTy)
         return Instruction::AddrSpaceCast;
       return 0;
+    }
     case 15:
       // FIXME: this state can be merged with (1), but the following assert
       // is useful to check the correcteness of the sequence due to semantic
Index: llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -2798,9 +2798,11 @@
   PointerType *SrcTy = cast<PointerType>(Src->getType()->getScalarType());
   PointerType *DestTy = cast<PointerType>(CI.getType()->getScalarType());
 
-  Type *DestElemTy = DestTy->getElementType();
-  if (SrcTy->getElementType() != DestElemTy) {
-    Type *MidTy = PointerType::get(DestElemTy, SrcTy->getAddressSpace());
+  Type *DestElemTy = !DestTy->isOpaque() ? DestTy->getElementType() : nullptr;
+  Type *SrcElemTy = !SrcTy->isOpaque() ? SrcTy->getElementType() : nullptr;
+  if (SrcElemTy != DestElemTy) {
+    Type *MidTy =
+        PointerType::getWithSamePointeeType(DestTy, SrcTy->getAddressSpace());
     // Handle vectors of pointers.
     if (VectorType *VT = dyn_cast<VectorType>(CI.getType()))
       MidTy = VectorType::get(MidTy, VT->getElementCount());
Index: llvm/test/Transforms/InstCombine/opaque-ptr.ll
===================================================================
--- llvm/test/Transforms/InstCombine/opaque-ptr.ll
+++ llvm/test/Transforms/InstCombine/opaque-ptr.ll
@@ -27,17 +27,41 @@
   ret i8* %b
 }
 
-;define ptr @addrspacecast_opaque_to_opaque(ptr addrspace(1) %a) {
-;  %b = addrspacecast ptr addrspace(1) %a to ptr
-;  ret ptr %b
-;}
+define ptr @addrspacecast_opaque_to_opaque(ptr addrspace(1) %a) {
+; CHECK-LABEL: @addrspacecast_opaque_to_opaque(
+; CHECK-NEXT:    [[B:%.*]] = addrspacecast ptr addrspace(1) [[A:%.*]] to ptr
+; CHECK-NEXT:    ret ptr [[B]]
+;
+  %b = addrspacecast ptr addrspace(1) %a to ptr
+  ret ptr %b
+}
+
+define ptr @addrspacecast_typed_to_opaque(i8 addrspace(1)* %a) {
+; CHECK-LABEL: @addrspacecast_typed_to_opaque(
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast i8 addrspace(1)* [[A:%.*]] to ptr addrspace(1)
+; CHECK-NEXT:    [[B:%.*]] = addrspacecast ptr addrspace(1) [[TMP1]] to ptr
+; CHECK-NEXT:    ret ptr [[B]]
+;
+  %b = addrspacecast i8 addrspace(1)* %a to ptr
+  ret ptr %b
+}
 
-;define ptr @addrspacecast_typed_to_opaque(i8 addrspace(1)* %a) {
-;  %b = addrspacecast i8 addrspace(1)* %a to ptr
-;  ret ptr %b
-;}
+define i8* @addrspacecast_opaque_to_typed(ptr addrspace(1) %a) {
+; CHECK-LABEL: @addrspacecast_opaque_to_typed(
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast ptr addrspace(1) [[A:%.*]] to i8 addrspace(1)*
+; CHECK-NEXT:    [[B:%.*]] = addrspacecast i8 addrspace(1)* [[TMP1]] to i8*
+; CHECK-NEXT:    ret i8* [[B]]
+;
+  %b = addrspacecast ptr addrspace(1) %a to i8*
+  ret i8* %b
+}
 
-;define i8* @addrspacecast_opaque_to_typed(ptr addrspace(1) %a) {
-;  %b = addrspacecast ptr addrspace(1) %a to i8*
-;  ret i8* %b
-;}
+define ptr addrspace(1) @bitcast_and_addrspacecast_eliminable(ptr %a) {
+; CHECK-LABEL: @bitcast_and_addrspacecast_eliminable(
+; CHECK-NEXT:    [[C:%.*]] = addrspacecast ptr [[A:%.*]] to ptr addrspace(1)
+; CHECK-NEXT:    ret ptr addrspace(1) [[C]]
+;
+  %b = bitcast ptr %a to i8*
+  %c = addrspacecast i8* %b to ptr addrspace(1)
+  ret ptr addrspace(1) %c
+}