Index: lib/Transforms/Utils/InlineFunction.cpp
===================================================================
--- lib/Transforms/Utils/InlineFunction.cpp
+++ lib/Transforms/Utils/InlineFunction.cpp
@@ -1811,9 +1811,12 @@
   }
 
   SmallVector<Value*,4> VarArgsToForward;
+  SmallVector<AttributeSet, 4> VarArgsAttrs;
   for (unsigned i = CalledFunc->getFunctionType()->getNumParams();
-       i < CS.getNumArgOperands(); i++)
+       i < CS.getNumArgOperands(); i++) {
     VarArgsToForward.push_back(CS.getArgOperand(i));
+    VarArgsAttrs.push_back(CS.getAttributes().getParamAttributes(i));
+  }
 
   bool InlinedMustTailCalls = false, InlinedDeoptimizeCalls = false;
   if (InlinedFunctionInfo.ContainsCalls) {
@@ -1835,6 +1838,20 @@
             ((ForwardVarArgsTo &&
               CI->getCalledFunction() == ForwardVarArgsTo) ||
              CI->isMustTailCall())) {
+          // Collect attributes for non-vararg parameters.
+          AttributeList Attrs = CI->getAttributes();
+          SmallVector<AttributeSet, 8> ArgAttrs;
+          if (!Attrs.isEmpty()) {
+            for (unsigned ArgNo = 0;
+                 ArgNo < CI->getFunctionType()->getNumParams(); ++ArgNo)
+              ArgAttrs.push_back(Attrs.getParamAttributes(ArgNo));
+          }
+
+          // Add VarArg attributes.
+          ArgAttrs.append(VarArgsAttrs.begin(), VarArgsAttrs.end());
+          Attrs = AttributeList::get(CI->getContext(), Attrs.getFnAttributes(),
+                                     Attrs.getRetAttributes(), ArgAttrs);
+          // Add VarArgs to existing parameters.
           SmallVector<Value *, 6> Params(CI->arg_operands());
           Params.append(VarArgsToForward.begin(), VarArgsToForward.end());
           CallInst *NewCI =
@@ -1842,6 +1859,7 @@
                                                        : CI->getCalledValue(),
                                Params, "", CI);
           NewCI->setDebugLoc(CI->getDebugLoc());
+          NewCI->setAttributes(Attrs);
           CI->replaceAllUsesWith(NewCI);
           CI->eraseFromParent();
           CI = NewCI;
Index: test/Transforms/Inline/inline-varargs.ll
===================================================================
--- test/Transforms/Inline/inline-varargs.ll
+++ test/Transforms/Inline/inline-varargs.ll
@@ -2,11 +2,11 @@
 ; RUN: opt < %s -passes='cgscc(inline,function(instcombine))' -S | FileCheck %s
 
 declare void @ext_method(i8*, i32)
-declare void @vararg_fn(i8*, ...)
+declare void @vararg_fn(...)
 
 define linkonce_odr void @thunk(i8* %this, ...) {
   %this_adj = getelementptr i8, i8* %this, i32 4
-  musttail call void (i8*, ...) bitcast (void (i8*, i32)* @ext_method to void (i8*, ...)*)(i8* %this_adj, ...)
+  musttail call void (i8*, ...) bitcast (void (i8*, i32)* @ext_method to void (i8*, ...)*)(i8* nonnull %this_adj, ...)
   ret void
 }
 
@@ -14,22 +14,34 @@
   call void (i8*, ...) @thunk(i8* %p, i32 42)
   ret void
 }
+; FIXME: instcombine should be able to simplify this to
+;        call void @ext_method(i8* %this_adj.i, i32 42)
 ; CHECK-LABEL: define void @thunk_caller(i8* %p)
-; CHECK: call void (i8*, ...) bitcast (void (i8*, i32)* @ext_method to void (i8*, ...)*)(i8* %this_adj.i, i32 42)
+; CHECK: call void (i8*, ...) bitcast (void (i8*, i32)* @ext_method to void (i8*, ...)*)(i8* nonnull %this_adj.i, i32 42)
 
-define void @test_callee_2(i8* %this, ...) {
-  %this_adj = getelementptr i8, i8* %this, i32 4
-  musttail call void (i8*, ...) @vararg_fn(i8* %this_adj, ...)
+define void @test_callee_2(...) {
+  musttail call void (...) @vararg_fn(...) #1
   ret void
 }
 
-define void @test_caller_2(i8* %p) {
-  call void (i8*, ...) @test_callee_2(i8* %p)
+define void @test_caller_2(i8* %p, i8* %q) {
+  call void (...) @test_callee_2(i8* %p, i8* byval %q)
   ret void
 }
-; CHECK-LABEL: define void @test_caller_2(i8* %p)
-; CHECK: call void (i8*, ...) @vararg_fn(i8* %this_adj.i)
+; CHECK-LABEL: define void @test_caller_2
+; CHECK: call void (...) @vararg_fn(i8* %p, i8* byval %q) [[FN_ATTRS:#[0-9]+]]
 
+define void @test_callee_3(i8* %p, ...) {
+  call void (...) @vararg_fn()
+  ret void
+}
+
+define void @test_caller_3(i8* %p, i8* %q) {
+  call void (i8*, ...) @test_callee_3(i8* nonnull %p, i8* %q)
+  ret void
+}
+; CHECK-LABEL: define void @test_caller_3
+; CHECK: call void (...) @vararg_fn()
 
 define internal i32 @varg_accessed(...) {
 entry:
@@ -50,3 +62,6 @@
 
 declare void @llvm.va_start(i8*)
 declare void @llvm.va_end(i8*)
+
+; CHECK: attributes [[FN_ATTRS]] = { "foo"="bar" }
+attributes #0 = { "foo"="bar" }