Index: lib/Analysis/ConstantFolding.cpp
===================================================================
--- lib/Analysis/ConstantFolding.cpp
+++ lib/Analysis/ConstantFolding.cpp
@@ -248,8 +248,7 @@
 
   // Look through ptr->int and ptr->ptr casts.
   if (CE->getOpcode() == Instruction::PtrToInt ||
-      CE->getOpcode() == Instruction::BitCast ||
-      CE->getOpcode() == Instruction::AddrSpaceCast)
+      CE->getOpcode() == Instruction::BitCast)
     return IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, DL);
 
   // i32* getelementptr ([5 x i32]* @a, i32 0, i32 5)
Index: test/Transforms/ConstProp/loads.ll
===================================================================
--- test/Transforms/ConstProp/loads.ll
+++ test/Transforms/ConstProp/loads.ll
@@ -40,13 +40,16 @@
   %r = load i16, i16 addrspace(1)* addrspacecast(i32* getelementptr ({{i32,i8},i32}, {{i32,i8},i32}* @g1, i32 0, i32 0, i32 0) to i16 addrspace(1)*)
   ret i16 %r
 
+; FIXME: Should be able to load through a constant addrspacecast.
 ; 0xBEEF
 ; LE-LABEL: @test2_addrspacecast(
-; LE: ret i16 -16657
+; XLE: ret i16 -16657
+; LE: load i16, i16 addrspace(1)* addrspacecast
 
 ; 0xDEAD
 ; BE-LABEL: @test2_addrspacecast(
-; BE: ret i16 -8531
+; XBE: ret i16 -8531
+; BE: load i16, i16 addrspace(1)* addrspacecast
 }
 
 ; Load of second 16 bits of 32-bit value.
Index: test/Transforms/Inline/inline-constexpr-addrspacecast-argument.ll
===================================================================
--- /dev/null
+++ test/Transforms/Inline/inline-constexpr-addrspacecast-argument.ll
@@ -0,0 +1,30 @@
+; RUN: opt -S -inline < %s | FileCheck %s
+
+target datalayout = "e-p3:32:32-p4:64:64-n32"
+
+@lds = internal addrspace(3) global [64 x i64] zeroinitializer
+
+; CHECK-LABEL: @constexpr_addrspacecast_ptr_size_change(
+; CHECK: load i64, i64 addrspace(4)* getelementptr (i64, i64 addrspace(4)* addrspacecast (i64 addrspace(3)* getelementptr inbounds ([64 x i64], [64 x i64] addrspace(3)* @lds, i32 0, i32 0) to i64 addrspace(4)*), i64 undef)
+; CHECK-NEXT: br
+define void @constexpr_addrspacecast_ptr_size_change() #0 {
+  %tmp0 = call i32 @foo(i64 addrspace(4)* addrspacecast (i64 addrspace(3)* getelementptr inbounds ([64 x i64], [64 x i64] addrspace(3)* @lds, i32 0, i32 0) to i64 addrspace(4)*)) #1
+  ret void
+}
+
+define i32 @foo(i64 addrspace(4)* %arg) #1 {
+bb:
+  %tmp = getelementptr i64, i64 addrspace(4)* %arg, i64 undef
+  %tmp1 = load i64, i64 addrspace(4)* %tmp
+  br i1 undef, label %bb2, label %bb3
+
+bb2:
+  store i64 0, i64 addrspace(4)* %tmp
+  br label %bb3
+
+bb3:
+  unreachable
+}
+
+attributes #0 = { nounwind }
+attributes #1 = { alwaysinline nounwind }