Index: llvm/trunk/lib/IR/Value.cpp
===================================================================
--- llvm/trunk/lib/IR/Value.cpp
+++ llvm/trunk/lib/IR/Value.cpp
@@ -490,8 +490,7 @@
         return V;
       Offset = GEPOffset;
       V = GEP->getPointerOperand();
-    } else if (Operator::getOpcode(V) == Instruction::BitCast ||
-               Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
+    } else if (Operator::getOpcode(V) == Instruction::BitCast) {
       V = cast<Operator>(V)->getOperand(0);
     } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
       V = GA->getAliasee();
Index: llvm/trunk/test/Transforms/LoopUnswitch/2015-09-18-Addrspace.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopUnswitch/2015-09-18-Addrspace.ll
+++ llvm/trunk/test/Transforms/LoopUnswitch/2015-09-18-Addrspace.ll
@@ -0,0 +1,28 @@
+; RUN: opt < %s -loop-unswitch -S | FileCheck %s
+
+; In cases where two address spaces do not have the same size pointer, the
+; input for the addrspacecast should not be used as a substitute for itself
+; when manipulating the pointer.
+
+target datalayout = "e-m:e-p:16:16-p1:32:16-i32:16-i64:16-n8:16"
+
+define void @foo() {
+; CHECK-LABEL: @foo
+entry:
+  %arrayidx.i1 = getelementptr inbounds i16, i16* undef, i16 undef
+  %arrayidx.i = addrspacecast i16* %arrayidx.i1 to i16 addrspace(1)*
+  br i1 undef, label %for.body.i, label %bar.exit
+
+for.body.i:                                       ; preds = %for.body.i, %entry
+; When we call makeLoopInvariant (i.e. trivial LICM) on this load, it 
+; will try to find the base object to prove deferenceability.  If we look
+; through the addrspacecast, we'll fail an assertion about bitwidths matching
+; CHECK-LABEL: for.body.i
+; CHECK:   %0 = load i16, i16 addrspace(1)* %arrayidx.i, align 2
+  %0 = load i16, i16 addrspace(1)* %arrayidx.i, align 2
+  %cmp1.i = icmp eq i16 %0, 0
+  br i1 %cmp1.i, label %bar.exit, label %for.body.i
+
+bar.exit:                                         ; preds = %for.body.i, %entry
+  ret void
+}