diff --git a/include/swift/Basic/LangOptions.h b/include/swift/Basic/LangOptions.h
index ea1c2bb2bc48a..3b9ad5d877206 100644
--- a/include/swift/Basic/LangOptions.h
+++ b/include/swift/Basic/LangOptions.h
@@ -1137,10 +1137,6 @@ namespace swift {
     /// ones to apply.
     bool LoadVersionIndependentAPINotes = false;
 
-    /// Whether the importer should skip SafeInteropWrappers, even though the
-    /// feature is enabled.
-    bool DisableSafeInteropWrappers = false;
-
     /// Return a hash code of any components from these options that should
     /// contribute to a Swift Bridging PCH hash.
     llvm::hash_code getPCHHashComponents() const {
diff --git a/lib/ClangImporter/SwiftifyDecl.cpp b/lib/ClangImporter/SwiftifyDecl.cpp
index 6d5b40bb655ce..d91b0a4b928ac 100644
--- a/lib/ClangImporter/SwiftifyDecl.cpp
+++ b/lib/ClangImporter/SwiftifyDecl.cpp
@@ -19,6 +19,7 @@
 #include "swift/AST/ASTPrinter.h"
 #include "swift/AST/Decl.h"
 #include "swift/AST/DiagnosticsClangImporter.h"
+#include "swift/AST/Import.h"
 #include "swift/AST/ParameterList.h"
 
 #include "clang/AST/ASTContext.h"
@@ -550,9 +551,22 @@ class SwiftifyProtocolInfoPrinter : public SwiftifyInfoPrinter {
   }
 };
 
+static bool shouldSkipModule(ModuleDecl *M) {
+  if (M->getName().str() == CLANG_HEADER_MODULE_NAME) {
+    DLOG("is from bridging header (or C++ namespace)\n");
+    return false;
+  }
+
+  if (M->getImplicitImportInfo().StdlibKind != ImplicitStdlibKind::Stdlib) {
+    DLOG("module " << M->getNameStr() << " does not import stdlib\n");
+    return true;
+  }
+
+  return false;
+}
+
 void ClangImporter::Implementation::swiftify(AbstractFunctionDecl *MappedDecl) {
-  if (!SwiftContext.LangOpts.hasFeature(Feature::SafeInteropWrappers) ||
-      SwiftContext.ClangImporterOpts.DisableSafeInteropWrappers)
+  if (!SwiftContext.LangOpts.hasFeature(Feature::SafeInteropWrappers))
     return;
   auto ClangDecl = dyn_cast_or_null<clang::FunctionDecl>(MappedDecl->getClangDecl());
   if (!ClangDecl)
@@ -563,6 +577,9 @@ void ClangImporter::Implementation::swiftify(AbstractFunctionDecl *MappedDecl) {
                    << MappedDecl->getName().getBaseName().userFacingName()
                    << "')\n");
 
+  if (shouldSkipModule(MappedDecl->getParentModule()))
+    return;
+
   {
     UnaliasedInstantiationVisitor visitor;
     visitor.TraverseType(ClangDecl->getType());
@@ -615,8 +632,7 @@ void ClangImporter::Implementation::swiftify(AbstractFunctionDecl *MappedDecl) {
 
 void ClangImporter::Implementation::swiftifyProtocol(
     NominalTypeDecl *MappedDecl) {
-  if (!SwiftContext.LangOpts.hasFeature(Feature::SafeInteropWrappers) ||
-      SwiftContext.ClangImporterOpts.DisableSafeInteropWrappers)
+  if (!SwiftContext.LangOpts.hasFeature(Feature::SafeInteropWrappers))
     return;
   if (!isa<ProtocolDecl, ClassDecl>(MappedDecl))
     return;
@@ -630,6 +646,10 @@ void ClangImporter::Implementation::swiftifyProtocol(
 
   DLOG_SCOPE("Checking '" << MappedDecl->getName()
               << "' protocol for methods with bounds and lifetime info\n");
+
+  if (shouldSkipModule(MappedDecl->getParentModule()))
+    return;
+
   llvm::SmallString<128> MacroString;
   {
     llvm::raw_svector_ostream out(MacroString);
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index d8d1719b1583b..4b5dba26ee228 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -2216,8 +2216,6 @@ static bool ParseClangImporterArgs(ClangImporterOptions &Opts, ArgList &Args,
 
   Opts.LoadVersionIndependentAPINotes |= Args.hasArg(OPT_version_independent_apinotes);
 
-  Opts.DisableSafeInteropWrappers |= FrontendOpts.ParseStdlib;
-
   if (FrontendOpts.DisableImplicitModules)
     Opts.DisableImplicitClangModules = true;
 
diff --git a/test/Interop/C/swiftify-import/memcmp.swift b/test/Interop/C/swiftify-import/memcmp.swift
new file mode 100644
index 0000000000000..b3e4eb89b1584
--- /dev/null
+++ b/test/Interop/C/swiftify-import/memcmp.swift
@@ -0,0 +1,32 @@
+// REQUIRES: swift_feature_SafeInteropWrappers
+
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// Prevent target SDK decl of memcmp (which may or may not have __sized_by annotations)
+// from being picked up as the canonical decl.
+// RUN: %empty-directory(%t/sdk)
+
+// RUN: %target-swift-frontend -emit-module -plugin-path %swift-plugin-dir -enable-experimental-feature SafeInteropWrappers -strict-memory-safety -sdk %t/sdk \
+// RUN:   -Xcc -Werror %t%{fs-sep}test.swift -import-objc-header %t%{fs-sep}test.h -verify -verify-additional-file %t%{fs-sep}test.h -Rmacro-expansions
+
+// Check that ClangImporter does not try to apply _SwiftifyImport to functions in SwiftShims,
+// as it does not import the standard library types.
+
+//--- test.swift
+public func callMemCmp1(_ p1: UnsafeMutableRawBufferPointer, _ p2: UnsafeMutableRawBufferPointer) {
+  // expected-error@+2{{missing argument for parameter #3 in call}}
+  // expected-error@+1 2{{cannot convert value of type 'UnsafeMutableRawBufferPointer' to expected argument type 'UnsafeRawPointer'}}
+  let _ = unsafe memcmp(p1, p2)
+}
+
+public func callMemCmp2(_ p1: UnsafeMutableRawPointer, _ p2: UnsafeMutableRawPointer) {
+  let _ = unsafe memcmp(p1, p2, 13)
+}
+
+//--- test.h
+#include <stddef.h>
+#define __sized_by(x) __attribute__((__sized_by__(x)))
+
+// expected-note@+1{{'memcmp' declared here}}
+int memcmp(const void * _Nullable __sized_by(n) s1, const void * _Nullable __sized_by(n) s2, size_t n);