diff --git a/mlir/include/mlir/IR/AttributeSupport.h b/mlir/include/mlir/IR/AttributeSupport.h
--- a/mlir/include/mlir/IR/AttributeSupport.h
+++ b/mlir/include/mlir/IR/AttributeSupport.h
@@ -79,7 +79,7 @@
 
 /// Base storage class appearing in an attribute. Derived storage classes should
 /// only be constructed within the context of the AttributeUniquer.
-class AttributeStorage : public StorageUniquer::BaseStorage {
+class alignas(8) AttributeStorage : public StorageUniquer::BaseStorage {
   friend detail::AttributeUniquer;
   friend StorageUniquer;
 
diff --git a/mlir/include/mlir/IR/Attributes.h b/mlir/include/mlir/IR/Attributes.h
--- a/mlir/include/mlir/IR/Attributes.h
+++ b/mlir/include/mlir/IR/Attributes.h
@@ -1714,7 +1714,8 @@
   static inline mlir::Attribute getFromVoidPointer(void *ptr) {
     return mlir::Attribute::getFromOpaquePointer(ptr);
   }
-  static constexpr int NumLowBitsAvailable = 3;
+  static constexpr int NumLowBitsAvailable = llvm::PointerLikeTypeTraits<
+      mlir::AttributeStorage *>::NumLowBitsAvailable;
 };
 
 template <>
diff --git a/mlir/lib/IR/AttributeDetail.h b/mlir/lib/IR/AttributeDetail.h
--- a/mlir/lib/IR/AttributeDetail.h
+++ b/mlir/lib/IR/AttributeDetail.h
@@ -84,7 +84,7 @@
   construct(AttributeStorageAllocator &allocator, const KeyTy &key) {
     auto size = DictionaryAttributeStorage::totalSizeToAlloc<NamedAttribute>(
         key.size());
-    auto rawMem = allocator.allocate(size, alignof(NamedAttribute));
+    auto rawMem = allocator.allocate(size, alignof(DictionaryAttributeStorage));
 
     // Initialize the storage and trailing attribute list.
     auto result = ::new (rawMem) DictionaryAttributeStorage(key.size());