diff --git a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
--- a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -462,7 +462,7 @@
   // SubclassData.  These are designed to fit within a uint16_t so they pack
   // with NodeType.
 
-#if defined(_AIX) && (!defined(__GNUC__) || defined(__ibmxl__))
+#if defined(_AIX) && (!defined(__GNUC__) || defined(__clang__))
 // Except for GCC; by default, AIX compilers store bit-fields in 4-byte words
 // and give the `pack` pragma push semantics.
 #define BEGIN_TWO_BYTE_PACK() _Pragma("pack(2)")
diff --git a/llvm/include/llvm/IR/BasicBlock.h b/llvm/include/llvm/IR/BasicBlock.h
--- a/llvm/include/llvm/IR/BasicBlock.h
+++ b/llvm/include/llvm/IR/BasicBlock.h
@@ -513,7 +513,7 @@
   void validateInstrOrdering() const;
 
 private:
-#if defined(_AIX) && (!defined(__GNUC__) || defined(__ibmxl__))
+#if defined(_AIX) && (!defined(__GNUC__) || defined(__clang__))
 // Except for GCC; by default, AIX compilers store bit-fields in 4-byte words
 // and give the `pack` pragma push semantics.
 #define BEGIN_TWO_BYTE_PACK() _Pragma("pack(2)")