diff --git a/src/librustc_codegen_ssa/mir/block.rs b/src/librustc_codegen_ssa/mir/block.rs
index 98da07a905e25..26442faa3215c 100644
--- a/src/librustc_codegen_ssa/mir/block.rs
+++ b/src/librustc_codegen_ssa/mir/block.rs
@@ -20,7 +20,7 @@ use syntax_pos::Pos;
 
 use super::{FunctionCx, LocalRef};
 use super::place::PlaceRef;
-use super::operand::{OperandValue, OperandRef};
+use super::operand::OperandRef;
 use super::operand::OperandValue::{Pair, Ref, Immediate};
 
 /// Used by `FunctionCx::codegen_terminator` for emitting common patterns
@@ -695,18 +695,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             // an "spoofed" `VaList`. This argument is ignored, but we need to
             // populate it with a dummy operand so that the users real arguments
             // are not overwritten.
-            let i = if sig.c_variadic && last_arg_idx.map(|x| x == i).unwrap_or(false) {
-                let layout = match self.cx.tcx().lang_items().va_list() {
-                    Some(did) => bx.cx().layout_of(bx.tcx().type_of(did)),
-                    None => bug!("`va_list` language item required for C-variadics"),
-                };
-                let op = OperandRef {
-                    val: OperandValue::Immediate(
-                        bx.cx().const_undef(bx.cx().immediate_backend_type(layout)
-                    )),
-                    layout: layout,
-                };
-                self.codegen_argument(&mut bx, op, &mut llargs, &fn_ty.args[i]);
+            let i = if sig.c_variadic && last_arg_idx.map(|x| i >= x).unwrap_or(false) {
                 if i + 1 < fn_ty.args.len() {
                     i + 1
                 } else {
diff --git a/src/test/codegen/c-variadic.rs b/src/test/codegen/c-variadic.rs
index 09c18ed90b216..cc2f95e1c28fd 100644
--- a/src/test/codegen/c-variadic.rs
+++ b/src/test/codegen/c-variadic.rs
@@ -1,4 +1,5 @@
 // compile-flags: -C no-prepopulate-passes
+// ignore-tidy-linelength
 
 #![crate_type = "lib"]
 #![feature(c_variadic)]
@@ -57,7 +58,7 @@ pub unsafe extern "C" fn c_variadic(n: i32, mut ap: ...) -> i32 {
 
 // Ensure that we generate the correct `call` signature when calling a Rust
 // defined C-variadic.
-pub unsafe fn test_c_variadic_call() {
+pub unsafe fn test_c_variadic_call_0() {
     // CHECK: call i32 (i32, ...) @c_variadic(i32 0)
     c_variadic(0);
     // CHECK: call i32 (i32, ...) @c_variadic(i32 0, i32 42)
@@ -67,3 +68,12 @@ pub unsafe fn test_c_variadic_call() {
     // CHECK: call i32 (i32, ...) @c_variadic(i32 0, i32 42, i32 1024, i32 0)
     c_variadic(0, 42i32, 1024i32, 0i32);
 }
+
+struct Foo(u64, u64);
+struct Bar(u64, u64, u64);
+
+// Ensure that emit arguments of the correct type.
+pub unsafe fn test_c_variadic_call_1() {
+    // CHECK: call void (i32, ...) @foreign_c_variadic_0(i32 0, { i64, i64 } %{{.*}}, %Bar* byval noalias nocapture dereferenceable(24) %{{.*}})
+    foreign_c_variadic_0(0, Foo(0, 0), Bar(0, 0, 0));
+}