diff --git a/lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp b/lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp
index 44da2a6458d8f..d30d9b4ca6691 100644
--- a/lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp
+++ b/lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp
@@ -13,6 +13,12 @@
 #include "swift/SILOptimizer/Utils/PerformanceInlinerUtils.h"
 #include "swift/AST/Module.h"
 #include "swift/SILOptimizer/Utils/InstOptUtils.h"
+#include "llvm/Support/CommandLine.h"
+
+llvm::cl::opt<std::string>
+    SILInlineNeverFuns("sil-inline-never-functions", llvm::cl::init(""),
+                       llvm::cl::desc("Never inline functions whose name "
+                                      "includes this string."));
 
 //===----------------------------------------------------------------------===//
 //                               ConstantTracker
@@ -687,6 +693,10 @@ SILFunction *swift::getEligibleFunction(FullApplySite AI,
     return nullptr;
   }
 
+  if (!SILInlineNeverFuns.empty()
+      && Callee->getName().find(SILInlineNeverFuns, 0) != StringRef::npos)
+    return nullptr;
+
   if (!Callee->shouldOptimize()) {
     return nullptr;
   }
diff --git a/test/SILOptimizer/array_contentof_opt.swift b/test/SILOptimizer/array_contentof_opt.swift
index aa218c2c6c88f..7d2af225a2a79 100644
--- a/test/SILOptimizer/array_contentof_opt.swift
+++ b/test/SILOptimizer/array_contentof_opt.swift
@@ -1,7 +1,16 @@
-// RUN: %target-swift-frontend -O -sil-verify-all -emit-sil %s | %FileCheck %s
+// RUN: %target-swift-frontend -O -sil-verify-all -emit-sil -Xllvm '-sil-inline-never-functions=$sSa6append' %s | %FileCheck %s
 // REQUIRES: swift_stdlib_no_asserts,optimized_stdlib
 
-// This is an end-to-end test of the array(contentsOf) -> array(Element) optimization
+// This is an end-to-end test of the Array.append(contentsOf:) ->
+// Array.append(Element) optimization.
+//
+// To check that the optimization produces the expected
+// Array.append(Element) calls, the CHECK lines match those call
+// sites. The optimizer may subsequently inline Array.append(Element),
+// which is good, but to keep the test simple and specific to the
+// optimization, the RUN line prevents inlining Array.append(Element).
+// Likewise, negative tests check for the existence of
+// Array.append(contentsOf:), so don't inline those either.
 
 // CHECK-LABEL: sil @{{.*}}testInt
 // CHECK-NOT: apply
@@ -22,14 +31,13 @@ public func testInt(_ a: inout [Int]) {
 // CHECK-DAG:    apply [[F]]
 // CHECK-DAG:    apply [[F]]
 // CHECK:      } // end sil function '{{.*}}testThreeInts{{.*}}'
-
 public func testThreeInts(_ a: inout [Int]) {
   a += [1, 2, 3]
 }
 
 // CHECK-LABEL: sil @{{.*}}testTooManyInts
 // CHECK-NOT: apply
-// CHECK:        [[F:%[0-9]+]] = function_ref  @$sSa6append10contentsOfyqd__n_t7ElementQyd__RszSTRd__lFSi_SaySiGTg5Tf4gn_n
+// CHECK:        [[F:%[0-9]+]] = function_ref  @$sSa6append10contentsOfyqd__n_t7ElementQyd__RszSTRd__lFSi_SaySiGTg5
 // CHECK-NOT: apply
 // CHECK:        apply [[F]]
 // CHECK-NOT: apply
@@ -57,7 +65,7 @@ public func dontPropagateContiguousArray(_ a: inout ContiguousArray<UInt8>) {
 
 // Check if the specialized Array.append<A>(contentsOf:) is reasonably optimized for Array<Int>.
 
-// CHECK-LABEL: sil shared {{.*}}@$sSa6append10contentsOfyqd__n_t7ElementQyd__RszSTRd__lFSi_SaySiGTg5
+// CHECK-LABEL: sil shared {{.*}}@$sSa6append10contentsOfyqd__n_t7ElementQyd__RszSTRd__lFSi_SaySiGTg5Tf4gn_n
 
 // There should only be a single call to _createNewBuffer or reserveCapacityForAppend/reserveCapacityImpl.
 
diff --git a/utils/swift-autocomplete.bash b/utils/swift-autocomplete.bash
index 7e48fd7d5fa85..d79094d0c64c4 100644
--- a/utils/swift-autocomplete.bash
+++ b/utils/swift-autocomplete.bash
@@ -68,6 +68,7 @@ _swift_complete()
       -sil-verify-without-invalidation \
       -sil-inline-test-threshold \
       -sil-inline-test \
+      -sil-inline-never-functions \
       -sroa-args-remove-dead-args-after \
       -ml \
       -sil-print-escapes \