diff --git a/lib/Transforms/IPO/InferFunctionAttrs.cpp b/lib/Transforms/IPO/InferFunctionAttrs.cpp
index 30402f1..c32e098 100644
--- a/lib/Transforms/IPO/InferFunctionAttrs.cpp
+++ b/lib/Transforms/IPO/InferFunctionAttrs.cpp
@@ -31,7 +31,8 @@
     // attribute logic on all calls to declarations (as declarations aren't
     // explicitly visited by CGSCC passes in the new pass manager.)
     if (F.isDeclaration() && !F.hasOptNone()) {
-      Changed |= inferLibFuncAttributes(F, GetTLI(F));
+      if (!F.hasFnAttribute(Attribute::NoBuiltin))
+        Changed |= inferLibFuncAttributes(F, GetTLI(F));
       Changed |= inferAttributesFromOthers(F);
     }
 
diff --git a/test/Transforms/InferFunctionAttrs/nobuiltin.ll b/test/Transforms/InferFunctionAttrs/nobuiltin.ll
new file mode 100644
index 0000000..1239a22
--- /dev/null
+++ b/test/Transforms/InferFunctionAttrs/nobuiltin.ll
@@ -0,0 +1,5 @@
+; RUN: opt -S -inferattrs < %s | FileCheck %s
+
+; CHECK: Function Attrs: nobuiltin allocsize(0)
+; CHECK: declare i8* @_Znwm(i32)
+declare i8* @_Znwm(i32) nobuiltin allocsize(0)