diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -1549,9 +1549,13 @@
                              const Twine &NamePrefix) {
   // Create i8 GEP for opaque pointers.
   if (Ptr->getType()->isOpaquePointerTy()) {
-    if (Offset != 0)
-      Ptr = IRB.CreateInBoundsGEP(IRB.getInt8Ty(), Ptr, IRB.getInt(Offset),
+    if (Offset != 0) {
+      Type *Int8Ty = IRB.getInt8Ty();
+      // This may fail due to alignment
+      assert(DL.getTypeAllocSize(Int8Ty) == 1 && "Unexpected I8 size!");
+      Ptr = IRB.CreateInBoundsGEP(Int8Ty, Ptr, IRB.getInt(Offset),
                                   NamePrefix + "sroa_idx");
+    }
     return IRB.CreatePointerBitCastOrAddrSpaceCast(Ptr, PointerTy,
                                                    NamePrefix + "sroa_cast");
   }
@@ -1640,11 +1644,14 @@
       Int8PtrOffset = Offset;
     }
 
-    OffsetPtr = Int8PtrOffset == 0
-                    ? Int8Ptr
-                    : IRB.CreateInBoundsGEP(IRB.getInt8Ty(), Int8Ptr,
-                                            IRB.getInt(Int8PtrOffset),
-                                            NamePrefix + "sroa_raw_idx");
+    Type *Int8Ty = IRB.getInt8Ty();
+    // This may fail due to alignment
+    assert(DL.getTypeAllocSize(Int8Ty) == 1 && "Unexpected I8 size!");
+    OffsetPtr =
+        Int8PtrOffset == 0
+            ? Int8Ptr
+            : IRB.CreateInBoundsGEP(Int8Ty, Int8Ptr, IRB.getInt(Int8PtrOffset),
+                                    NamePrefix + "sroa_raw_idx");
   }
   Ptr = OffsetPtr;