Index: clang/lib/Basic/Targets/PPC.h
===================================================================
--- clang/lib/Basic/Targets/PPC.h
+++ clang/lib/Basic/Targets/PPC.h
@@ -369,7 +369,8 @@
   }
 
   BuiltinVaListKind getBuiltinVaListKind() const override {
-    // This is the ELF definition, and is overridden by the Darwin sub-target
+    // This is the ELF definition, and is overridden by the Darwin and AIX
+    // sub-target.
     return TargetInfo::PowerABIBuiltinVaList;
   }
 };
Index: clang/lib/CodeGen/TargetInfo.cpp
===================================================================
--- clang/lib/CodeGen/TargetInfo.cpp
+++ clang/lib/CodeGen/TargetInfo.cpp
@@ -4229,7 +4229,10 @@
 // DefaultABIInfo::EmitVAArg.
 Address PPC32_SVR4_ABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAList,
                                       QualType Ty) const {
-  if (getTarget().getTriple().isOSDarwin()) {
+  // TODO: Add AIX ABI Info.  Currently we are relying on PPC32_SVR4_ABIInfo to
+  // emit correct VAArg.
+  if (getTarget().getTriple().isOSDarwin() ||
+      getTarget().getTriple().isOSAIX()) {
     auto TI = getContext().getTypeInfoInChars(Ty);
     TI.second = getParamTypeAlignment(Ty);
 
Index: clang/test/CodeGen/aix-vararg.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/aix-vararg.c
@@ -0,0 +1,30 @@
+// REQUIRES: powerpc-registered-target
+// REQUIRES: asserts
+// RUN: %clang_cc1 -triple powerpc-ibm-aix-xcoff -emit-llvm -o - %s | FileCheck %s --check-prefix=32BIT
+#include <stdarg.h>
+
+void aix_varg(int a, ...) {
+  va_list arg;
+  va_start(arg, a);
+  va_arg(arg, int);
+  va_end(arg);
+}
+
+// 32BIT:           define void @aix_varg(i32 %a, ...) #0 {
+// 32BIT:           entry:
+// 32BIT-NEXT:        %a.addr = alloca i32, align 4
+// 32BIT-NEXT:        %arg = alloca i8*, align 4
+// 32BIT-NEXT:        store i32 %a, i32* %a.addr, align 4
+// 32BIT-NEXT:        %arg1 = bitcast i8** %arg to i8*
+// 32BIT-NEXT:        call void @llvm.va_start(i8* %arg1)
+// 32BIT-NEXT:        %argp.cur = load i8*, i8** %arg, align 4
+// 32BIT-NEXT:        %argp.next = getelementptr inbounds i8, i8* %argp.cur, i32 4
+// 32BIT-NEXT:        store i8* %argp.next, i8** %arg, align 4
+// 32BIT-NEXT:        %0 = bitcast i8* %argp.cur to i32*
+// 32BIT-NEXT:        %1 = load i32, i32* %0, align 4
+// 32BIT-NEXT:        %arg2 = bitcast i8** %arg to i8*
+// 32BIT-NEXT:        call void @llvm.va_end(i8* %arg2)
+// 32BIT-NEXT:        ret void
+// 32BIT-NEXT:      }
+// 32BIT:            declare void @llvm.va_start(i8*)
+// 32BIT:            declare void @llvm.va_end(i8*)