diff --git a/test/Transforms/InstCombine/strncpy_chk-1.ll b/test/Transforms/InstCombine/strncpy_chk-1.ll
new file mode 100644
index 00000000000..ae7e2fb5f18
--- /dev/null
+++ b/test/Transforms/InstCombine/strncpy_chk-1.ll
@@ -0,0 +1,66 @@
+; Test lib call simplification of __strncpy_chk calls with various values
+; for len and dstlen.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+
+@a = common global [60 x i8] zeroinitializer, align 1
+@b = common global [60 x i8] zeroinitializer, align 1
+@.str = private constant [8 x i8] c"abcdefg\00"
+
+; Check cases where dstlen >= len
+
+define void @test_simplify1() {
+; CHECK: @test_simplify1
+  %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
+  %src = getelementptr inbounds [8 x i8]* @.str, i32 0, i32 0
+
+; CHECK-NEXT: call i8* @strncpy
+  call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 60)
+  ret void
+}
+
+define void @test_simplify2() {
+; CHECK: @test_simplify2
+  %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
+  %src = getelementptr inbounds [8 x i8]* @.str, i32 0, i32 0
+
+; CHECK-NEXT: call i8* @strncpy
+  call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 8)
+  ret void
+}
+
+define void @test_simplify3() {
+; CHECK: @test_simplify3
+  %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
+  %src = getelementptr inbounds [60 x i8]* @b, i32 0, i32 0
+
+; CHECK-NEXT: call i8* @strncpy
+  call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 60)
+  ret void
+}
+
+; Check cases where dstlen < len
+
+define void @test_no_simplify1() {
+; CHECK: @test_no_simplify1
+  %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
+  %src = getelementptr inbounds [8 x i8]* @.str, i32 0, i32 0
+
+; CHECK-NEXT: call i8* @__strncpy_chk
+  call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 4)
+  ret void
+}
+
+define void @test_no_simplify2() {
+; CHECK: @test_no_simplify2
+  %dst = getelementptr inbounds [60 x i8]* @a, i32 0, i32 0
+  %src = getelementptr inbounds [60 x i8]* @b, i32 0, i32 0
+
+; CHECK-NEXT: call i8* @__strncpy_chk
+  call i8* @__strncpy_chk(i8* %dst, i8* %src, i32 8, i32 0)
+  ret void
+}
+
+declare i8* @__strncpy_chk(i8*, i8*, i32, i32)
diff --git a/test/Transforms/InstCombine/strncpy_chk-2.ll b/test/Transforms/InstCombine/strncpy_chk-2.ll
new file mode 100644
index 00000000000..a0f132ebf63
--- /dev/null
+++ b/test/Transforms/InstCombine/strncpy_chk-2.ll
@@ -0,0 +1,21 @@
+; Test that lib call simplification doesn't simplify __strncpy_chk calls
+; with the wrong prototype.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+
+@a = common global [60 x i16] zeroinitializer, align 1
+@b = common global [60 x i16] zeroinitializer, align 1
+
+define void @test_no_simplify() {
+; CHECK: @test_no_simplify
+  %dst = getelementptr inbounds [60 x i16]* @a, i32 0, i32 0
+  %src = getelementptr inbounds [60 x i16]* @b, i32 0, i32 0
+
+; CHECK-NEXT: call i16* @__strncpy_chk
+  call i16* @__strncpy_chk(i16* %dst, i16* %src, i32 60, i32 60)
+  ret void
+}
+
+declare i16* @__strncpy_chk(i16*, i16*, i32, i32)