Index: lib/CodeGen/TargetInfo.cpp
===================================================================
--- lib/CodeGen/TargetInfo.cpp
+++ lib/CodeGen/TargetInfo.cpp
@@ -3543,9 +3543,23 @@
       Builder.CreateStructGEP(VAList, 3, CharUnits::fromQuantity(4));
     Address OverflowArea(Builder.CreateLoad(OverflowAreaAddr),
                          OverflowAreaAlign);
-
-    // The current address is the address of the varargs element.
-    // FIXME: do we not need to round up to alignment?
+    // Round up address of argument to alignment
+    llvm::Value *overflow_arg_area = OverflowArea.getPointer();
+    uint32_t Align = CGF.getContext().getTypeAlignInChars(Ty).getQuantity();
+    if (Align > 4) {
+      // overflow_arg_area = (overflow_arg_area + align - 1) & -align;
+      llvm::Value *Offset = llvm::ConstantInt::get(CGF.Int32Ty, Align - 1);
+      overflow_arg_area = CGF.Builder.CreateGEP(overflow_arg_area, Offset);
+      llvm::Value *AsInt = CGF.Builder.CreatePtrToInt(overflow_arg_area,
+                                                      CGF.Int32Ty);
+      llvm::Value *Mask = llvm::ConstantInt::get(CGF.Int32Ty, -(uint32_t)Align);
+      overflow_arg_area =
+        CGF.Builder.CreateIntToPtr(CGF.Builder.CreateAnd(AsInt, Mask),
+                                   overflow_arg_area->getType(),
+                                   "overflow_arg_area.align");
+    }
+ 
+    OverflowArea = Address(overflow_arg_area, CharUnits::fromQuantity(Align));
     MemAddr = Builder.CreateElementBitCast(OverflowArea, DirectTy);
 
     // Increase the overflow area.
Index: test/CodeGen/ppc-varargs-struct.c
===================================================================
--- test/CodeGen/ppc-varargs-struct.c
+++ test/CodeGen/ppc-varargs-struct.c
@@ -39,9 +39,13 @@
 // CHECK-PPC:[[USING_OVERFLOW]]
 // CHECK-PPC-NEXT:  [[OVERFLOW_AREA_P:%[0-9]+]] = getelementptr inbounds %struct.__va_list_tag, %struct.__va_list_tag* [[ARRAYDECAY]], i32 0, i32 3
 // CHECK-PPC-NEXT:  [[OVERFLOW_AREA:%.+]] = load i8*, i8** [[OVERFLOW_AREA_P]], align 4
-// CHECK-PPC-NEXT:  [[MEMADDR:%.+]] = bitcast i8* [[OVERFLOW_AREA]] to %struct.x**
-// CHECK-PPC-NEXT:  [[NEW_OVERFLOW_AREA:%[0-9]+]] = getelementptr inbounds i8, i8* [[OVERFLOW_AREA]], i32 4
-// CHECK-PPC-NEXT:  store i8* [[NEW_OVERFLOW_AREA]], i8** [[OVERFLOW_AREA_P]]
+// CHECK-PPC-NEXT:  %{{[0-9]+}} = getelementptr i8, i8* %{{[0-9]+}}, i32 7
+// CHECK-PPC-NEXT:  %{{[0-9]+}} = ptrtoint i8* %{{[0-9]+}} to i32
+// CHECK-PPC-NEXT:  %{{[0-9]+}} = and i32 %{{[0-9]+}}, -8
+// CHECK-PPC-NEXT:  %overflow_arg_area.align = inttoptr i32 %{{[0-9]+}} to i8*
+// CHECK-PPC-NEXT:  [[MEMADDR:%.+]] = bitcast i8* %overflow_arg_area.align to %struct.x**
+// CHECK-PPC-NEXT:  [[NEW_OVERFLOW_AREA:%[0-9]+]] = getelementptr inbounds i8, i8* %overflow_arg_area.align, i32 4
+// CHECK-PPC-NEXT:  store i8* [[NEW_OVERFLOW_AREA:%[0-9]+]], i8** [[OVERFLOW_AREA_P]], align 4
 // CHECK-PPC-NEXT:  br label %[[CONT]]
 //
 // CHECK-PPC:[[CONT]]