Index: llvm/lib/Transforms/IPO/FunctionAttrs.cpp
===================================================================
--- llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -720,9 +720,20 @@
         // Note that we don't allow any calls at all here, or else our result
         // will be dependent on the iteration order through the functions in the
         // SCC.
-        SmallPtrSet<Argument *, 8> Self;
-        Self.insert(&*A);
-        Attribute::AttrKind R = determinePointerReadAttrs(&*A, Self);
+
+        Attribute::AttrKind R = Attribute::ReadNone;
+        // Strengthen the attribute of a pointer argument A from WriteOnly
+        // to ReadNone when its uses is empty i.e. there is no actual
+        // write through nor read from the pointer argument A.
+        if (A->hasAttribute(Attribute::WriteOnly) &&
+            (A->materialized_use_empty())) {
+          A->removeAttr(Attribute::WriteOnly);
+        } else {
+          SmallPtrSet<Argument *, 8> Self;
+          Self.insert(&*A);
+          R = determinePointerReadAttrs(&*A, Self);
+        }
+
         if (R != Attribute::None) {
           A->addAttr(R);
           Changed = true;
Index: llvm/test/Transforms/FunctionAttrs/writeonly.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/FunctionAttrs/writeonly.ll
@@ -0,0 +1,30 @@
+; RUN: opt < %s -functionattrs         -S | FileCheck %s
+; RUN: opt < %s -passes=function-attrs -S | FileCheck %s
+
+; CHECK: define void @nouses-argworn-funrn(i32* nocapture readnone %.aaa) #0 {
+define void @nouses-argworn-funrn(i32* writeonly %.aaa) {
+nouses-argworn-funrn_entry:
+  ret void
+}
+
+; CHECK: define void @nouses-argworn-funro(i32* nocapture readnone %.aaa, i32* nocapture readonly %.bbb) #1 {
+define void @nouses-argworn-funro(i32* writeonly %.aaa, i32* %.bbb) {
+nouses-argworn-funro_entry:
+  %val = load i32 , i32* %.bbb
+  ret void
+}
+
+%_type_of_d-ccc = type <{ i8*, i8, i8, i8, i8 }>
+
+@d-ccc = internal global %_type_of_d-ccc <{ i8* null, i8 1, i8 13, i8 0, i8 -127 }>, align 8
+
+; CHECK: define void @nouses-argworn-funwo(i32* nocapture readnone %.aaa) #2 {
+define void @nouses-argworn-funwo(i32* writeonly %.aaa) {
+nouses-argworn-funwo_entry:
+  store i8 0, i8* getelementptr inbounds (%_type_of_d-ccc, %_type_of_d-ccc* @d-ccc, i32 0, i32 3)
+  ret void
+}
+
+; CHECK: attributes #0 = { norecurse nounwind readnone }
+; CHECK: attributes #1 = { norecurse nounwind readonly }
+; CHECK: attributes #2 = { norecurse nounwind writeonly }