diff --git a/include/llvm/Target/TargetData.h b/include/llvm/Target/TargetData.h
index 4f94ab7..c97af7d 100644
--- a/include/llvm/Target/TargetData.h
+++ b/include/llvm/Target/TargetData.h
@@ -53,10 +53,10 @@
 /// @note The unusual order of elements in the structure attempts to reduce
 /// padding and make the structure slightly more cache friendly.
 struct TargetAlignElem {
-  AlignTypeEnum       AlignType : 8;  ///< Alignment type (AlignTypeEnum)
-  unsigned            ABIAlign;       ///< ABI alignment for this type/bitw
-  unsigned            PrefAlign;      ///< Pref. alignment for this type/bitw
-  uint32_t            TypeBitWidth;   ///< Type bit width
+  uint32_t AlignType    : 8;  ///< Alignment type (AlignTypeEnum)
+  uint32_t TypeBitWidth : 24; ///< Type bit width
+  uint32_t ABIAlign     : 16; ///< ABI alignment for this type/bitw
+  uint32_t PrefAlign    : 16; ///< Pref. alignment for this type/bitw
 
   /// Initializer
   static TargetAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
diff --git a/lib/Target/TargetData.cpp b/lib/Target/TargetData.cpp
index cc6dc1e..0040147 100644
--- a/lib/Target/TargetData.cpp
+++ b/lib/Target/TargetData.cpp
@@ -314,6 +314,8 @@
 TargetData::setAlignment(AlignTypeEnum align_type, unsigned abi_align,
                          unsigned pref_align, uint32_t bit_width) {
   assert(abi_align <= pref_align && "Preferred alignment worse than ABI!");
+  assert(pref_align < (1 << 16) && "Alignment doesn't fit in bitfield");
+  assert(bit_width < (1 << 24) && "Bit width doesn't fit in bitfield");
   for (unsigned i = 0, e = Alignments.size(); i != e; ++i) {
     if (Alignments[i].AlignType == align_type &&
         Alignments[i].TypeBitWidth == bit_width) {