diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 9f7d58a4a3cd6..a5a784027636f 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -8123,7 +8123,8 @@ class Sema final {
                             SourceLocation EllipsisLoc);
 
   bool AttachTypeConstraint(AutoTypeLoc TL,
-                            NonTypeTemplateParmDecl *ConstrainedParameter,
+                            NonTypeTemplateParmDecl *NewConstrainedParm,
+                            NonTypeTemplateParmDecl *OrigConstrainedParm,
                             SourceLocation EllipsisLoc);
 
   bool RequireStructuralType(QualType T, SourceLocation Loc);
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index befc1e73c4f35..f1de491f1cd33 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1251,35 +1251,41 @@ bool Sema::AttachTypeConstraint(NestedNameSpecifierLoc NS,
   return false;
 }
 
-bool Sema::AttachTypeConstraint(AutoTypeLoc TL, NonTypeTemplateParmDecl *NTTP,
+bool Sema::AttachTypeConstraint(AutoTypeLoc TL,
+                                NonTypeTemplateParmDecl *NewConstrainedParm,
+                                NonTypeTemplateParmDecl *OrigConstrainedParm,
                                 SourceLocation EllipsisLoc) {
-  if (NTTP->getType() != TL.getType() ||
+  if (NewConstrainedParm->getType() != TL.getType() ||
       TL.getAutoKeyword() != AutoTypeKeyword::Auto) {
-    Diag(NTTP->getTypeSourceInfo()->getTypeLoc().getBeginLoc(),
+    Diag(NewConstrainedParm->getTypeSourceInfo()->getTypeLoc().getBeginLoc(),
          diag::err_unsupported_placeholder_constraint)
-       << NTTP->getTypeSourceInfo()->getTypeLoc().getSourceRange();
+        << NewConstrainedParm->getTypeSourceInfo()
+               ->getTypeLoc()
+               .getSourceRange();
     return true;
   }
   // FIXME: Concepts: This should be the type of the placeholder, but this is
   // unclear in the wording right now.
   DeclRefExpr *Ref =
-      BuildDeclRefExpr(NTTP, NTTP->getType(), VK_PRValue, NTTP->getLocation());
+      BuildDeclRefExpr(OrigConstrainedParm, OrigConstrainedParm->getType(),
+                       VK_PRValue, OrigConstrainedParm->getLocation());
   if (!Ref)
     return true;
   ExprResult ImmediatelyDeclaredConstraint = formImmediatelyDeclaredConstraint(
       *this, TL.getNestedNameSpecifierLoc(), TL.getConceptNameInfo(),
       TL.getNamedConcept(), TL.getLAngleLoc(), TL.getRAngleLoc(),
-      BuildDecltypeType(Ref), NTTP->getLocation(),
+      BuildDecltypeType(Ref), OrigConstrainedParm->getLocation(),
       [&](TemplateArgumentListInfo &ConstraintArgs) {
         for (unsigned I = 0, C = TL.getNumArgs(); I != C; ++I)
           ConstraintArgs.addArgument(TL.getArgLoc(I));
       },
       EllipsisLoc);
   if (ImmediatelyDeclaredConstraint.isInvalid() ||
-     !ImmediatelyDeclaredConstraint.isUsable())
+      !ImmediatelyDeclaredConstraint.isUsable())
     return true;
 
-  NTTP->setPlaceholderTypeConstraint(ImmediatelyDeclaredConstraint.get());
+  NewConstrainedParm->setPlaceholderTypeConstraint(
+      ImmediatelyDeclaredConstraint.get());
   return false;
 }
 
@@ -1559,7 +1565,7 @@ NamedDecl *Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
 
   if (AutoTypeLoc TL = TInfo->getTypeLoc().getContainedAutoTypeLoc())
     if (TL.isConstrained())
-      if (AttachTypeConstraint(TL, Param, D.getEllipsisLoc()))
+      if (AttachTypeConstraint(TL, Param, Param, D.getEllipsisLoc()))
         Invalid = true;
 
   if (Invalid)
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index bf82ffb52a26e..ce461b18978c4 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -3008,8 +3008,10 @@ Decl *TemplateDeclInstantiator::VisitNonTypeTemplateParmDecl(
 
   if (AutoTypeLoc AutoLoc = DI->getTypeLoc().getContainedAutoTypeLoc())
     if (AutoLoc.isConstrained())
+      // Note: We attach the uninstantiated constriant here, so that it can be
+      // instantiated relative to the top level, like all our other constraints.
       if (SemaRef.AttachTypeConstraint(
-              AutoLoc, Param,
+              AutoLoc, Param, D,
               IsExpandedParameterPack
                 ? DI->getTypeLoc().getAs<PackExpansionTypeLoc>()
                     .getEllipsisLoc()
diff --git a/clang/test/SemaTemplate/concepts.cpp b/clang/test/SemaTemplate/concepts.cpp
index bf5896a14991b..d28c2b22bd045 100644
--- a/clang/test/SemaTemplate/concepts.cpp
+++ b/clang/test/SemaTemplate/concepts.cpp
@@ -792,3 +792,27 @@ int foo() {
     return b;
 }
 } // namespace GH48182
+
+namespace GH61777 {
+template<class T> concept C = sizeof(T) == 4; // #61777_C
+template<class T, class U> concept C2 = sizeof(T) == sizeof(U); //#61777_C2
+
+template<class T>
+struct Parent {
+  template<class, C auto> struct TakesUnary { static const int i = 0 ; }; // #UNARY
+  template<class, C2<T> auto> struct TakesBinary { static const int i = 0 ; }; //#BINARY
+};
+
+static_assert(Parent<void>::TakesUnary<int, 0>::i == 0);
+// expected-error@+3{{constraints not satisfied for class template 'TakesUnary'}}
+// expected-note@#UNARY{{because 'decltype(0ULL)' (aka 'unsigned long long') does not satisfy 'C'}}
+// expected-note@#61777_C{{because 'sizeof(unsigned long long) == 4' (8 == 4) evaluated to false}}
+static_assert(Parent<void>::TakesUnary<int, 0uLL>::i == 0);
+
+static_assert(Parent<int>::TakesBinary<int, 0>::i == 0);
+// expected-error@+3{{constraints not satisfied for class template 'TakesBinary'}}
+// expected-note@#BINARY{{because 'C2<decltype(0ULL), int>' evaluated to false}}
+// expected-note@#61777_C2{{because 'sizeof(unsigned long long) == sizeof(int)' (8 == 4) evaluated to false}}
+static_assert(Parent<int>::TakesBinary<int, 0ULL>::i == 0);
+}
+