Index: lib/Transforms/Utils/BuildLibCalls.cpp
===================================================================
--- lib/Transforms/Utils/BuildLibCalls.cpp
+++ lib/Transforms/Utils/BuildLibCalls.cpp
@@ -690,6 +690,8 @@
   //case LibFunc::memset_pattern8:
   case LibFunc::memset_pattern16:
     Changed |= setOnlyAccessesArgMemory(F);
+    Changed |= setDoesNotCapture(F, 1);
+    Changed |= setDoesNotCapture(F, 2);
     Changed |= setOnlyReadsMemory(F, 2);
     return Changed;
   // int __nvvm_reflect(const char *)
Index: test/Transforms/InferFunctionAttrs/annotate.ll
===================================================================
--- test/Transforms/InferFunctionAttrs/annotate.ll
+++ test/Transforms/InferFunctionAttrs/annotate.ll
@@ -25,7 +25,7 @@
 
 declare void @memset_pattern16(i8*, i8*, i64)
 ; CHECK: declare void @memset_pattern16(i8*, i8*, i64)
-; CHECK-POSIX: declare void @memset_pattern16(i8*, i8* readonly, i64) [[G2:#[0-9]+]]
+; CHECK-POSIX: declare void @memset_pattern16(i8* nocapture, i8* nocapture readonly, i64) [[G2:#[0-9]+]]
 
 declare i32 @gettimeofday(i8*, i8*)
 ; CHECK-POSIX: declare i32 @gettimeofday(i8* nocapture, i8* nocapture) [[G0:#[0-9]+]]