Index: clang/include/clang/AST/ASTContext.h
===================================================================
--- clang/include/clang/AST/ASTContext.h
+++ clang/include/clang/AST/ASTContext.h
@@ -2673,6 +2673,11 @@
   /// that they may be used in declarations of the same template.
   bool isSameTemplateParameter(const NamedDecl *X, const NamedDecl *Y) const;
 
+  /// Determine whether two 'requires' expressions are similar enough.
+  /// Use of 'requires' isn't mandatory, works with constraints expressed in
+  /// other ways too.
+  bool isSameConstraintExpr(const Expr *XCE, const Expr *YCE) const;
+
   /// Determine whether two default template arguments are similar enough
   /// that they may be used in declarations of the same template.
   bool isSameDefaultTemplateArgument(const NamedDecl *X,
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -6218,6 +6218,19 @@
          getCanonicalTemplateName(Y).getAsVoidPointer();
 }
 
+bool ASTContext::isSameConstraintExpr(const Expr *XCE, const Expr *YCE) const {
+  if (!XCE != !YCE)
+    return false;
+
+  if (!XCE)
+    return true;
+
+  llvm::FoldingSetNodeID XCEID, YCEID;
+  XCE->Profile(XCEID, *this, /*Canonical=*/true);
+  YCE->Profile(YCEID, *this, /*Canonical=*/true);
+  return XCEID == YCEID;
+}
+
 bool ASTContext::isSameTemplateParameter(const NamedDecl *X,
                                          const NamedDecl *Y) const {
   if (X->getKind() != Y->getKind())
@@ -6245,14 +6258,23 @@
         auto *TYTCArgs = TYTC->getTemplateArgsAsWritten();
         if (TXTCArgs->NumTemplateArgs != TYTCArgs->NumTemplateArgs)
           return false;
-        llvm::FoldingSetNodeID XID, YID;
-        for (auto &ArgLoc : TXTCArgs->arguments())
-          ArgLoc.getArgument().Profile(XID, X->getASTContext());
-        for (auto &ArgLoc : TYTCArgs->arguments())
-          ArgLoc.getArgument().Profile(YID, Y->getASTContext());
-        if (XID != YID)
-          return false;
+        // We couldn't compare the profiling result for the template
+        // args here. Consider the following example in different modules:
+        //
+        // template <__integer_like _Tp, C<_Tp> Sentinel>
+        // constexpr _Tp operator()(_Tp &&__t, Sentinel &&last) const {
+        //   return __t;
+        // }
+        //
+        // When we compare the profiling result for `C<_Tp>` in different
+        // modules, it will compare the type of `_Tp` in different modules.
+        // However, the type of `_Tp` in different modules refer to different
+        // types here naturally. So we couldn't compare the profiling result
+        // for the template args directly.
       }
+      if (!isSameConstraintExpr(TXTC->getImmediatelyDeclaredConstraint(),
+                                TYTC->getImmediatelyDeclaredConstraint()))
+        return false;
     }
     return true;
   }
@@ -6279,19 +6301,7 @@
     if (!isSameTemplateParameter(X->getParam(I), Y->getParam(I)))
       return false;
 
-  const Expr *XRC = X->getRequiresClause();
-  const Expr *YRC = Y->getRequiresClause();
-  if (!XRC != !YRC)
-    return false;
-  if (XRC) {
-    llvm::FoldingSetNodeID XRCID, YRCID;
-    XRC->Profile(XRCID, *this, /*Canonical=*/true);
-    YRC->Profile(YRCID, *this, /*Canonical=*/true);
-    if (XRCID != YRCID)
-      return false;
-  }
-
-  return true;
+  return isSameConstraintExpr(X->getRequiresClause(), Y->getRequiresClause());
 }
 
 bool ASTContext::isSameDefaultTemplateArgument(const NamedDecl *X,
@@ -6489,17 +6499,9 @@
         return false;
     }
 
-    const Expr *XRC = FuncX->getTrailingRequiresClause();
-    const Expr *YRC = FuncY->getTrailingRequiresClause();
-    if (!XRC != !YRC)
+    if (!isSameConstraintExpr(FuncX->getTrailingRequiresClause(),
+                              FuncY->getTrailingRequiresClause()))
       return false;
-    if (XRC) {
-      llvm::FoldingSetNodeID XRCID, YRCID;
-      XRC->Profile(XRCID, *this, /*Canonical=*/true);
-      YRC->Profile(YRCID, *this, /*Canonical=*/true);
-      if (XRCID != YRCID)
-        return false;
-    }
 
     auto GetTypeAsWritten = [](const FunctionDecl *FD) {
       // Map to the first declaration that we've already merged into this one.
Index: clang/test/Modules/concept.cppm
===================================================================
--- clang/test/Modules/concept.cppm
+++ clang/test/Modules/concept.cppm
@@ -3,6 +3,7 @@
 // RUN: split-file %s %t
 //
 // RUN: %clang_cc1 -std=c++20 %t/A.cppm -emit-module-interface -o %t/A.pcm
+// RUN: %clang_cc1 -std=c++20 -fprebuilt-module-path=%t -I%t -DDIFFERENT %t/B.cppm -verify
 // RUN: %clang_cc1 -std=c++20 -fprebuilt-module-path=%t -I%t %t/B.cppm -verify
 
 //--- foo.h
@@ -18,6 +19,9 @@
 template <class _Tp>
 concept __member_size = requires(_Tp &&t) { t.size(); };
 
+template <class First, class Second>
+concept C = requires(First x, Second y) { x + y; };
+
 struct A {
 public:
   template <Range T>
@@ -29,6 +33,29 @@
   constexpr __integer_like auto operator()(_Tp&& __t) const {
     return __t.size();
   }
+
+  template <__integer_like _Tp, C<_Tp> Sentinel>
+  constexpr _Tp operator()(_Tp &&__t, Sentinel &&last) const {
+    return __t;
+  }
+
+  template <template <class> class H, class S, C<H<S>> Sentinel>
+  constexpr H<S> operator()(H<S> &&__s, Sentinel &&last) const {
+    return __s;
+  }
+
+// Tests that we could find different concept definition indeed.
+#ifndef DIFFERENT
+  template <__integer_like _Tp, __integer_like _Up, C<_Tp> Sentinel>
+  constexpr _Tp operator()(_Tp &&__t, _Up _u, Sentinel &&last) const {
+    return __t;
+  }
+#else
+  template <__integer_like _Tp, __integer_like _Up, C<_Up> Sentinel>
+  constexpr _Tp operator()(_Tp &&__t, _Up _u, Sentinel &&last) const {
+    return __t;
+  }
+#endif
 };
 #endif
 
@@ -38,12 +65,23 @@
 export module A;
 
 //--- B.cppm
-// expected-no-diagnostics
 module;
 #include "foo.h"
 export module B;
 import A;
 
+#ifdef DIFFERENT
+// expected-error@foo.h:41 {{'__fn::operator()' from module 'A.<global>' is not present in definition of '__fn' provided earlier}}
+// expected-note@* 1+{{declaration of 'operator()' does not match}}
+#else
+// expected-no-diagnostics
+#endif
+
+template <class T>
+struct U {
+  auto operator+(U) { return 0; }
+};
+
 void foo() {
     A a;
     struct S {
@@ -51,4 +89,8 @@
         auto operator+(S s) { return 0; }
     };
     __fn{}(S());
+    __fn{}(S(), S());
+    __fn{}(S(), S(), S());
+
+    __fn{}(U<int>(), U<int>());
 }