diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -598,8 +598,7 @@
   }
   // C++2b features.
   if (LangOpts.CPlusPlus2b) {
-    if (!LangOpts.MSVCCompat)
-      Builder.defineMacro("__cpp_implicit_move", "202011L");
+    Builder.defineMacro("__cpp_implicit_move", "202011L");
     Builder.defineMacro("__cpp_size_t_suffix", "202011L");
   }
   if (LangOpts.Char8)
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -3307,6 +3307,21 @@
   return new (Context) BreakStmt(BreakLoc);
 }
 
+static bool CheckSimplerImplicitMovesMSVCWorkaround(const Sema &S,
+                                                    const Expr &E) {
+  if (!S.getLangOpts().MSVCCompat)
+    return false;
+  const Decl *D = E.getReferencedDeclOfCallee();
+  if (!S.SourceMgr.isInSystemHeader(D->getLocation()))
+    return false;
+  for (const DeclContext *DC = D->getDeclContext(); DC; DC = DC->getParent()) {
+    if (const auto *NS = dyn_cast<NamespaceDecl>(DC))
+      if (NS->isStdNamespace())
+        return true;
+  }
+  return false;
+}
+
 /// Determine whether the given expression might be move-eligible or
 /// copy-elidable in either a (co_)return statement or throw expression,
 /// without considering function return type, if applicable.
@@ -3338,8 +3353,8 @@
   //        as the MSVC STL has issues with this change.
   //        We will come back later with a more targeted approach.
   if (Res.Candidate && !E->isXValue() &&
-      (ForceCXX2b ||
-       (getLangOpts().CPlusPlus2b && !getLangOpts().MSVCCompat))) {
+      (ForceCXX2b || (getLangOpts().CPlusPlus2b &&
+                      !CheckSimplerImplicitMovesMSVCWorkaround(*this, *E)))) {
     E = ImplicitCastExpr::Create(Context, VD->getType().getNonReferenceType(),
                                  CK_NoOp, E, nullptr, VK_XValue,
                                  FPOptionsOverride());
diff --git a/clang/test/SemaCXX/Inputs/sys/cxx2b-p2266-disable-with-msvc-compat-sys.hpp b/clang/test/SemaCXX/Inputs/sys/cxx2b-p2266-disable-with-msvc-compat-sys.hpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaCXX/Inputs/sys/cxx2b-p2266-disable-with-msvc-compat-sys.hpp
@@ -0,0 +1,33 @@
+int &&st1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &st2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+
+namespace {
+int &&st1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &st2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace
+
+namespace foo {
+int &&st1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &st2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+namespace std {
+int &&st1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &st2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace std
+} // namespace foo
+
+namespace std {
+
+int &&st1(int &&x) { return x; } // old-error {{cannot bind to lvalue}}
+int &st2(int &&x) { return x; }  // new-error {{cannot bind to a temporary}}
+
+namespace {
+int &&st1(int &&x) { return x; } // old-error {{cannot bind to lvalue}}
+int &st2(int &&x) { return x; }  // new-error {{cannot bind to a temporary}}
+} // namespace
+
+namespace foo {
+int &&st1(int &&x) { return x; } // old-error {{cannot bind to lvalue}}
+int &st2(int &&x) { return x; }  // new-error {{cannot bind to a temporary}}
+} // namespace foo
+
+} // namespace std
diff --git a/clang/test/SemaCXX/Inputs/usr/cxx2b-p2266-disable-with-msvc-compat-usr.hpp b/clang/test/SemaCXX/Inputs/usr/cxx2b-p2266-disable-with-msvc-compat-usr.hpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaCXX/Inputs/usr/cxx2b-p2266-disable-with-msvc-compat-usr.hpp
@@ -0,0 +1,33 @@
+int &&ut1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &ut2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+
+namespace {
+int &&ut1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &ut2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace
+
+namespace foo {
+int &&ut1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &ut2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+namespace std {
+int &&ut1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &ut2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace std
+} // namespace foo
+
+namespace std {
+
+int &&ut1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &ut2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+
+namespace {
+int &&ut1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &ut2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace
+
+namespace foo {
+int &&ut1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &ut2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace foo
+
+} // namespace std
diff --git a/clang/test/SemaCXX/cxx2b-p2266-disable-with-msvc-compat.cpp b/clang/test/SemaCXX/cxx2b-p2266-disable-with-msvc-compat.cpp
--- a/clang/test/SemaCXX/cxx2b-p2266-disable-with-msvc-compat.cpp
+++ b/clang/test/SemaCXX/cxx2b-p2266-disable-with-msvc-compat.cpp
@@ -1,50 +1,48 @@
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -fcxx-exceptions                    -verify=new %s
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -fcxx-exceptions -fms-compatibility -verify=old %s
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -fcxx-exceptions                    -verify=old %s
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -I %S/Inputs/usr -isystem %S/Inputs/sys                    -verify=cxx2b,new %s
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -I %S/Inputs/usr -isystem %S/Inputs/sys -fms-compatibility -verify=cxx2b,old %s
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -I %S/Inputs/usr -isystem %S/Inputs/sys                    -verify=cxx20,old %s
 
 // FIXME: This is a test for a temporary workaround where we disable simpler implicit moves
-//        when compiling with -fms-compatibility, because the MSVC STL does not compile.
-//        A better workaround is under discussion.
-//        The test cases here are just a copy from `CXX/class/class.init/class.copy.elision/p3.cpp`,
-//        so feel free to delete this file when the workaround is not needed anymore.
-
-struct CopyOnly {
-  CopyOnly(); // new-note {{candidate constructor not viable: requires 0 arguments, but 1 was provided}}
-  // new-note@-1 {{candidate constructor not viable: requires 0 arguments, but 1 was provided}}
-  CopyOnly(CopyOnly &); // new-note {{candidate constructor not viable: expects an lvalue for 1st argument}}
-  // new-note@-1 {{candidate constructor not viable: expects an lvalue for 1st argument}}
-};
-struct MoveOnly {
-  MoveOnly();
-  MoveOnly(MoveOnly &&);
-};
-MoveOnly &&rref();
-
-MoveOnly &&test1(MoveOnly &&w) {
-  return w; // old-error {{cannot bind to lvalue of type}}
-}
-
-CopyOnly test2(bool b) {
-  static CopyOnly w1;
-  CopyOnly w2;
-  if (b) {
-    return w1;
-  } else {
-    return w2; // new-error {{no matching constructor for initialization}}
-  }
-}
-
-template <class T> T &&test3(T &&x) { return x; } // old-error {{cannot bind to lvalue of type}}
-template MoveOnly &test3<MoveOnly &>(MoveOnly &);
-template MoveOnly &&test3<MoveOnly>(MoveOnly &&); // old-note {{in instantiation of function template specialization}}
-
-MoveOnly &&test4() {
-  MoveOnly &&x = rref();
-  return x; // old-error {{cannot bind to lvalue of type}}
-}
-
-void test5() try {
-  CopyOnly x;
-  throw x; // new-error {{no matching constructor for initialization}}
-} catch (...) {
-}
+//        in the STL when compiling with -fms-compatibility, because of issues with the
+//        implementation there.
+//        Feel free to delete this file when the workaround is not needed anymore.
+
+#if __cpluscplus > 202002L && __cpp_implicit_move < 202011L
+#error "__cpp_implicit_move not defined correctly"
+#endif
+
+int &&mt1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &mt2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+
+namespace {
+int &&mt1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &mt2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace
+
+namespace foo {
+int &&mt1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &mt2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+namespace std {
+int &&mt1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &mt2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace std
+} // namespace foo
+
+namespace std {
+
+int &&mt1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &mt2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+
+namespace {
+int &&mt1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &mt2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace
+
+namespace foo {
+int &&mt1(int &&x) { return x; } // cxx20-error {{cannot bind to lvalue}}
+int &mt2(int &&x) { return x; }  // cxx2b-error {{cannot bind to a temporary}}
+} // namespace foo
+
+} // namespace std
+#include <cxx2b-p2266-disable-with-msvc-compat-usr.hpp>
+#include <cxx2b-p2266-disable-with-msvc-compat-sys.hpp>