diff --git a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 0034ddf63a4..58c61e7de9f 100644
--- a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -180,7 +180,10 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
       // Now that I is pointing to the first non-allocation-inst in the block,
       // insert our getelementptr instruction...
       //
-      Value *NullIdx = Constant::getNullValue(Type::getInt32Ty(AI.getContext()));
+      Type *IdxTy = TD
+                  ? TD->getIntPtrType(AI.getContext())
+                  : Type::getInt64Ty(AI.getContext());
+      Value *NullIdx = Constant::getNullValue(IdxTy);
       Value *Idx[2] = { NullIdx, NullIdx };
       Instruction *GEP =
         GetElementPtrInst::CreateInBounds(New, Idx, New->getName() + ".sub");
@@ -300,9 +303,11 @@ static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
       if (ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
         if (Constant *CSrc = dyn_cast<Constant>(CastOp))
           if (ASrcTy->getNumElements() != 0) {
-            Value *Idxs[2];
-            Idxs[0] = Constant::getNullValue(Type::getInt32Ty(LI.getContext()));
-            Idxs[1] = Idxs[0];
+            Type *IdxTy = TD
+                        ? TD->getIntPtrType(LI.getContext())
+                        : Type::getInt64Ty(LI.getContext());
+            Value *Idx = Constant::getNullValue(IdxTy);
+            Value *Idxs[2] = { Idx, Idx };
             CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
             SrcTy = cast<PointerType>(CastOp->getType());
             SrcPTy = SrcTy->getElementType();
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index 768f466107f..248c3498ba4 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1235,9 +1235,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
       if (TD && SrcElTy->isArrayTy() &&
           TD->getTypeAllocSize(SrcElTy->getArrayElementType()) ==
           TD->getTypeAllocSize(ResElTy)) {
-        Value *Idx[2];
-        Idx[0] = Constant::getNullValue(Type::getInt32Ty(GEP.getContext()));
-        Idx[1] = GEP.getOperand(1);
+        Type *IdxType = TD->getIntPtrType(GEP.getContext());
+        Value *Idx[2] = { Constant::getNullValue(IdxType), GEP.getOperand(1) };
         Value *NewGEP = GEP.isInBounds() ?
           Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()) :
           Builder->CreateGEP(StrippedPtr, Idx, GEP.getName());
@@ -1304,9 +1303,11 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
             // Successfully decomposed Idx as NewIdx * Scale, form a new GEP.
             // If the multiplication NewIdx * Scale may overflow then the new
             // GEP may not be "inbounds".
-            Value *Off[2];
-            Off[0] = Constant::getNullValue(Type::getInt32Ty(GEP.getContext()));
-            Off[1] = NewIdx;
+            Value *Off[2] = {
+              Constant::getNullValue(TD->getIntPtrType(GEP.getContext())),
+              NewIdx
+            };
+
             Value *NewGEP = GEP.isInBounds() && NSW ?
               Builder->CreateInBoundsGEP(StrippedPtr, Off, GEP.getName()) :
               Builder->CreateGEP(StrippedPtr, Off, GEP.getName());
diff --git a/test/Transforms/InstCombine/alloca.ll b/test/Transforms/InstCombine/alloca.ll
index 9a80ad9df62..ae1cfa1ed2f 100644
--- a/test/Transforms/InstCombine/alloca.ll
+++ b/test/Transforms/InstCombine/alloca.ll
@@ -1,7 +1,7 @@
-target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128"
+; RUN: opt < %s -instcombine -S -default-data-layout="E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128" | FileCheck %s
+; RUN: opt < %s -instcombine -S -default-data-layout="E-p:32:32:32-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128" | FileCheck %s -check-prefix=P32
+; RUN: opt < %s -instcombine -S | FileCheck %s -check-prefix=NODL
 
-; RUN: opt < %s -instcombine -S | FileCheck %s
-; END.
 
 declare void @use(...)
 
@@ -110,3 +110,22 @@ entry:
 }
 
 declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
+
+
+; Check that the GEP indices use the pointer size, or 64 if unknown
+define void @test8() {
+; CHECK-LABEL: @test8(
+; CHECK: alloca [100 x i32]
+; CHECK: getelementptr inbounds [100 x i32]* %x1, i64 0, i64 0
+
+; P32-LABEL: @test8(
+; P32: alloca [100 x i32]
+; P32: getelementptr inbounds [100 x i32]* %x1, i32 0, i32 0
+
+; NODL-LABEL: @test8(
+; NODL: alloca [100 x i32]
+; NODL: getelementptr inbounds [100 x i32]* %x1, i64 0, i64 0
+  %x = alloca i32, i32 100
+  call void (...)* @use(i32* %x)
+  ret void
+}