diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index abb6bb747bfa9..54b5e3877782d 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -2500,7 +2500,20 @@ void ASTWriter::WriteDeclAbbrevs() {
 /// relatively painless since they would presumably only do it for top-level
 /// decls.
 static bool isRequiredDecl(const Decl *D, ASTContext &Context,
-                           bool WritingModule) {
+                           Module *WritingModule) {
+  // Named modules have different semantics than header modules. Every named
+  // module units owns a translation unit. So the importer of named modules
+  // doesn't need to deserilize everything ahead of time.
+  if (WritingModule && WritingModule->isModulePurview()) {
+    // The PragmaCommentDecl and PragmaDetectMismatchDecl are MSVC's extension.
+    // And the behavior of MSVC for such cases will leak this to the module
+    // users. Given pragma is not a standard thing, the compiler has the space
+    // to do their own decision. Let's follow MSVC here.
+    if (isa<PragmaCommentDecl, PragmaDetectMismatchDecl>(D))
+      return true;
+    return false;
+  }
+
   // An ObjCMethodDecl is never considered as "required" because its
   // implementation container always is.
 
diff --git a/clang/test/Modules/no-eager-load.cppm b/clang/test/Modules/no-eager-load.cppm
new file mode 100644
index 0000000000000..6632cc60c8eb8
--- /dev/null
+++ b/clang/test/Modules/no-eager-load.cppm
@@ -0,0 +1,110 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: cd %t
+//
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/a.cppm -o %t/a.pcm
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/b.cppm -o %t/b.pcm
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %t/c.cpp \
+// RUN:     -fprebuilt-module-path=%t
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %t/d.cpp \
+// RUN:     -fprebuilt-module-path=%t
+//
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/e.cppm -o %t/e.pcm
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/f.cppm -o %t/f.pcm
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %t/g.cpp \
+// RUN:     -fprebuilt-module-path=%t
+//
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/h.cppm \
+// RUN:     -fprebuilt-module-path=%t -o %t/h.pcm
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/i.cppm \
+// RUN:     -fprebuilt-module-path=%t -o %t/i.pcm
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %t/j.cpp \
+// RUN:     -fprebuilt-module-path=%t
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %t/k.cpp \
+// RUN:     -fprebuilt-module-path=%t
+
+//--- a.cppm
+export module a;
+export void foo() {
+
+}
+
+//--- b.cppm
+export module b;
+void bar();
+export void foo() {
+    bar();
+}
+
+//--- c.cpp
+// expected-no-diagnostics
+// Since we will load all the declaration lazily, we won't be able to find
+// the ODR violation here.
+import a;
+import b;
+
+//--- d.cpp
+import a;
+import b;
+// Test that we can still check the odr violation if we call the function
+// actually.
+void use() {
+    foo(); // expected-error@* {{'foo' has different definitions in different modules;}}
+           // expected-note@* {{but in 'a' found a different body}}
+}
+
+//--- foo.h
+void foo() {
+
+}
+
+//--- bar.h
+void bar();
+void foo() {
+    bar();
+}
+
+//--- e.cppm
+module;
+#include "foo.h"
+export module e;
+export using ::foo;
+
+//--- f.cppm
+module;
+#include "bar.h"
+export module f;
+export using ::foo;
+
+//--- g.cpp
+import e;
+import f;
+void use() {
+    foo(); // expected-error@* {{'foo' has different definitions in different modules;}}
+           // expected-note@* {{but in 'e.<global>' found a different body}}
+}
+
+//--- h.cppm
+export module h;
+export import a;
+export import b;
+
+//--- i.cppm
+export module i;
+export import e;
+export import f;
+
+//--- j.cpp
+import h;
+void use() {
+    foo(); // expected-error@* {{'foo' has different definitions in different modules;}}
+           // expected-note@* {{but in 'a' found a different body}}
+}
+
+//--- k.cpp
+import i;
+void use() {
+    foo(); // expected-error@* {{'foo' has different definitions in different modules;}}
+           // expected-note@* {{but in 'e.<global>' found a different body}}
+}
+
diff --git a/clang/test/Modules/pr61783.cppm b/clang/test/Modules/pr61783.cppm
new file mode 100644
index 0000000000000..9cf773b0b282b
--- /dev/null
+++ b/clang/test/Modules/pr61783.cppm
@@ -0,0 +1,29 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-pc-windows-msvc19.11.0 -fms-extensions %t/mod.cppm -emit-module-interface \
+// RUN:     -o %t/mod.pcm
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-pc-windows-msvc19.11.0 -fms-extensions %t/mod.pcm -S -emit-llvm -o - | \
+// RUN:     FileCheck %t/mod.cppm
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-pc-windows-msvc19.11.0 -fms-extensions %t/user.cpp -fmodule-file=mod=%t/mod.pcm \
+// RUN:     -S -emit-llvm -o - | FileCheck %t/user.cpp
+
+//--- mod.cppm
+module;
+
+#pragma comment(lib, "msvcprt.lib")
+#pragma detect_mismatch("myLib_version", "9")
+
+export module mod;
+
+// CHECK: ![[NUM:[0-9]+]] ={{.*}}msvcprt.lib
+// CHECK: ![[NUM:[0-9]+]] ={{.*}}FAILIFMISMATCH{{.*}}myLib_version=9
+
+//--- user.cpp
+#pragma detect_mismatch("myLib_version", "1")
+import mod;
+
+// CHECK: ![[NUM:[0-9]+]] ={{.*}}FAILIFMISMATCH{{.*}}myLib_version=1
+// CHECK: ![[NUM:[0-9]+]] ={{.*}}msvcprt.lib
+// CHECK: ![[NUM:[0-9]+]] ={{.*}}FAILIFMISMATCH{{.*}}myLib_version=9