diff --git a/test/Transforms/InstCombine/memcpy_chk-1.ll b/test/Transforms/InstCombine/memcpy_chk-1.ll
new file mode 100644
index 00000000000..7c7d91808a3
--- /dev/null
+++ b/test/Transforms/InstCombine/memcpy_chk-1.ll
@@ -0,0 +1,60 @@
+; Test lib call simplification of __memcpy_chk calls with various values
+; for dstlen and len.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+
+%struct.T1 = type { [100 x i32], [100 x i32], [1024 x i8] }
+%struct.T2 = type { [100 x i32], [100 x i32], [1024 x i8] }
+%struct.T3 = type { [100 x i32], [100 x i32], [2048 x i8] }
+
+@t1 = common global %struct.T1 zeroinitializer
+@t2 = common global %struct.T2 zeroinitializer
+@t3 = common global %struct.T3 zeroinitializer
+
+; Check cases where dstlen >= len.
+
+define void @test_simplify1() {
+; CHECK: @test_simplify1
+  %dst = bitcast %struct.T1* @t1 to i8*
+  %src = bitcast %struct.T2* @t2 to i8*
+
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64
+  call i8* @__memcpy_chk(i8* %dst, i8* %src, i64 1824, i64 1824)
+  ret void
+}
+
+define void @test_simplify2() {
+; CHECK: @test_simplify2
+  %dst = bitcast %struct.T1* @t1 to i8*
+  %src = bitcast %struct.T3* @t3 to i8*
+
+; CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64
+  call i8* @__memcpy_chk(i8* %dst, i8* %src, i64 1824, i64 2848)
+  ret void
+}
+
+; Check cases where dstlen < len.
+
+define void @test_no_simplify1() {
+; CHECK: @test_no_simplify1
+  %dst = bitcast %struct.T3* @t3 to i8*
+  %src = bitcast %struct.T1* @t1 to i8*
+
+; CHECK-NEXT: call i8* @__memcpy_chk
+  call i8* @__memcpy_chk(i8* %dst, i8* %src, i64 2848, i64 1824)
+  ret void
+}
+
+define void @test_no_simplify2() {
+; CHECK: @test_no_simplify2
+  %dst = bitcast %struct.T1* @t1 to i8*
+  %src = bitcast %struct.T2* @t2 to i8*
+
+; CHECK-NEXT: call i8* @__memcpy_chk
+  call i8* @__memcpy_chk(i8* %dst, i8* %src, i64 1024, i64 0)
+  ret void
+}
+
+declare i8* @__memcpy_chk(i8*, i8*, i64, i64)
diff --git a/test/Transforms/InstCombine/memcpy_chk-2.ll b/test/Transforms/InstCombine/memcpy_chk-2.ll
new file mode 100644
index 00000000000..aa43029d47f
--- /dev/null
+++ b/test/Transforms/InstCombine/memcpy_chk-2.ll
@@ -0,0 +1,24 @@
+; Test that lib call simplification doesn't simplify __memcpy_chk calls
+; with the wrong prototype.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+
+%struct.T1 = type { [100 x i32], [100 x i32], [1024 x i8] }
+%struct.T2 = type { [100 x i32], [100 x i32], [1024 x i8] }
+
+@t1 = common global %struct.T1 zeroinitializer
+@t2 = common global %struct.T2 zeroinitializer
+
+define void @test_no_simplify() {
+; CHECK: @test_no_simplify
+  %dst = bitcast %struct.T1* @t1 to i8*
+  %src = bitcast %struct.T2* @t2 to i8*
+
+; CHECK-NEXT: call i8* @__memcpy_chk
+  call i8* @__memcpy_chk(i8* %dst, i8* %src, i64 1824)
+  ret void
+}
+
+declare i8* @__memcpy_chk(i8*, i8*, i64)