diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 4182986aa13a8c..482791ada5d1a0 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -6687,6 +6687,10 @@ bool ASTContext::isSameEntity(const NamedDecl *X, const NamedDecl *Y) const {
                               FuncY->getTrailingRequiresClause()))
       return false;
 
+    // Constrained friends are different in certain cases, see: [temp.friend]p9.
+    if (FriendsDifferByConstraints(FuncX, FuncY))
+      return false;
+
     auto GetTypeAsWritten = [](const FunctionDecl *FD) {
       // Map to the first declaration that we've already merged into this one.
       // The TSI of redeclarations might not match (due to calling conventions