--- /dev/null
+; RUN: opt -function-specialization -force-function-specialization -S < %s | FileCheck %s
+
+; Function @foo has function attribute 'noduplicate', so check that we don't
+; specialize it:
+
+; CHECK-NOT: @foo.1(
+; CHECK-NOT: @foo.2(
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+
+@A = external dso_local constant i32, align 4
+@B = external dso_local constant i32, align 4
+
+define dso_local i32 @bar(i32 %x, i32 %y) {
+entry:
+ %tobool = icmp ne i32 %x, 0
+ br i1 %tobool, label %if.then, label %if.else
+
+if.then:
+ %call = call i32 @foo(i32 %x, i32* @A)
+ br label %return
+
+if.else:
+ %call1 = call i32 @foo(i32 %y, i32* @B)
+ br label %return
+
+return:
+ %retval.0 = phi i32 [ %call, %if.then ], [ %call1, %if.else ]
+ ret i32 %retval.0
+}
+
+define internal i32 @foo(i32 %x, i32* %b) #0 {
+entry:
+ %0 = load i32, i32* %b, align 4
+ %add = add nsw i32 %x, %0
+ ret i32 %add
+}
+
+attributes #0 = { noduplicate }