Index: mlir/include/mlir/IR/AttributeSupport.h
===================================================================
--- mlir/include/mlir/IR/AttributeSupport.h
+++ 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;
 
Index: mlir/include/mlir/IR/Attributes.h
===================================================================
--- mlir/include/mlir/IR/Attributes.h
+++ mlir/include/mlir/IR/Attributes.h
@@ -1699,7 +1699,8 @@
   static inline mlir::Attribute getFromVoidPointer(void *ptr) {
     return mlir::Attribute::getFromOpaquePointer(ptr);
   }
-  static constexpr int NumLowBitsAvailable = 3;
+  static constexpr int NumLowBitsAvailable =
+      llvm::CTLog2<alignof(mlir::AttributeStorage)>();
 };
 
 template <>
Index: mlir/lib/IR/AttributeDetail.h
===================================================================
--- mlir/lib/IR/AttributeDetail.h
+++ 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());