Index: lib/Target/X86/X86CallingConv.td
===================================================================
--- lib/Target/X86/X86CallingConv.td
+++ lib/Target/X86/X86CallingConv.td
@@ -642,7 +642,7 @@
 
   // Integer/FP values get stored in stack slots that are 8 bytes in size and
   // 8-byte aligned if there are no more registers to hold them.
-  CCIfType<[i32, i64, f32, f64], CCAssignToStack<8, 8>>
+  CCIfType<[i8, i16, i32, i64, f32, f64], CCAssignToStack<8, 8>>
 ]>;
 
 def CC_X86_Win64_VectorCall : CallingConv<[
Index: test/CodeGen/X86/win64-smallparams.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/win64-smallparams.ll
@@ -0,0 +1,19 @@
+; RUN: llc < %s -mtriple=x86_64-windows-msvc | FileCheck %s --check-prefix=CHECK
+; RUN: llc < %s -mtriple=x86_64-windows-gnu | FileCheck %s --check-prefix=CHECK
+
+define dso_local void @call() {
+entry:
+  tail call void @manyargs(i8 1, i16 2, i8 3, i16 4, i8 5, i16 6)
+  ret void
+}
+
+declare dso_local void @manyargs(i8, i16, i8, i16, i8, i16)
+
+; CHECK-LABEL: call:
+; CHECK-DAG: movw $6, 40(%rsp)
+; CHECK-DAG: movb $5, 32(%rsp)
+; CHECK-DAG: movb $1, %cl
+; CHECK-DAG: movw $2, %dx
+; CHECK-DAG: movb $3, %r8b
+; CHECK-DAG: movw $4, %r9w
+; CHECK: callq manyargs