Index: lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- lib/Transforms/InstCombine/InstructionCombining.cpp
+++ lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2034,6 +2034,7 @@
     }
   }
 
+  // Try to infer inbounds on GEPs of allocas.
   if (!GEP.isInBounds()) {
     unsigned IdxWidth =
         DL.getIndexSizeInBits(PtrOp->getType()->getPointerAddressSpace());
@@ -2045,7 +2046,8 @@
       if (GEP.accumulateConstantOffset(DL, BasePtrOffset) &&
           BasePtrOffset.isNonNegative()) {
         APInt AllocSize(IdxWidth, DL.getTypeAllocSize(AI->getAllocatedType()));
-        if (BasePtrOffset.ule(AllocSize)) {
+        if (BasePtrOffset.ule(AllocSize) && GEP.getAddressSpace() ==
+            PtrOp->getType()->getPointerAddressSpace()) {
           return GetElementPtrInst::CreateInBounds(
               PtrOp, makeArrayRef(Ops).slice(1), GEP.getName());
         }
Index: test/Transforms/InstCombine/getelementptr.ll
===================================================================
--- test/Transforms/InstCombine/getelementptr.ll
+++ test/Transforms/InstCombine/getelementptr.ll
@@ -942,4 +942,17 @@
   ret <2 x i32*> %tmp1
 }
 
+; Test that inbounds inference does not crash in the presence of addrspacecasts.
+define i8 addrspace(42)* @gep_inbounds_addrspace() {
+; CHECK-LABEL: @gep_inbounds_addrspace
+; CHECK: addrspacecast
+; CHECK: getelementptr
+; CHECK: ret
+  %A = alloca <8 x half>, align 16
+  %B = bitcast <8 x half>* %A to i8*
+  %C = addrspacecast i8* %B to i8 addrspace(42)*
+  %gep = getelementptr i8, i8 addrspace(42)* %C, i64 12
+  ret i8 addrspace(42)* %gep
+}
+
 ; CHECK: attributes [[$NUW]] = { nounwind }