diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 8e5dbeb792348..1adb81ad358b7 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -4297,6 +4297,15 @@ class TreeTransform {
     return getSema().OpenACC().ActOnOpenACCAsteriskSizeExpr(AsteriskLoc);
   }
 
+  ExprResult
+  RebuildSubstNonTypeTemplateParmExpr(Decl *AssociatedDecl,
+                                      const NonTypeTemplateParmDecl *NTTP,
+                                      SourceLocation Loc, TemplateArgument Arg,
+                                      UnsignedOrNone PackIndex, bool Final) {
+    return getSema().BuildSubstNonTypeTemplateParmExpr(
+        AssociatedDecl, NTTP, Loc, Arg, PackIndex, Final);
+  }
+
 private:
   QualType TransformTypeInObjectScope(TypeLocBuilder &TLB, TypeLoc TL,
                                       QualType ObjectType,
@@ -16459,7 +16468,7 @@ ExprResult TreeTransform<Derived>::TransformSubstNonTypeTemplateParmPackExpr(
 
   TemplateArgument Pack = E->getArgumentPack();
   TemplateArgument Arg = SemaRef.getPackSubstitutedTemplateArgument(Pack);
-  return SemaRef.BuildSubstNonTypeTemplateParmExpr(
+  return getDerived().RebuildSubstNonTypeTemplateParmExpr(
       E->getAssociatedDecl(), E->getParameterPack(),
       E->getParameterPackLocation(), Arg, SemaRef.getPackIndex(Pack),
       E->getFinal());
@@ -16517,10 +16526,10 @@ ExprResult TreeTransform<Derived>::TransformSubstNonTypeTemplateParmExpr(
     Replacement = E->getReplacement();
   }
 
-  return new (SemaRef.Context) SubstNonTypeTemplateParmExpr(
-      Replacement.get()->getType(), Replacement.get()->getValueKind(),
-      E->getNameLoc(), Replacement.get(), AssociatedDecl, E->getIndex(),
-      E->getPackIndex(), E->isReferenceParameter(), E->getFinal());
+  return getDerived().RebuildSubstNonTypeTemplateParmExpr(
+      AssociatedDecl, E->getParameter(), E->getNameLoc(),
+      TemplateArgument(Replacement.get(), /*IsCanonical=*/false),
+      E->getPackIndex(), E->getFinal());
 }
 
 template<typename Derived>
diff --git a/clang/test/SemaTemplate/concepts.cpp b/clang/test/SemaTemplate/concepts.cpp
index c90af41a09468..eed8b786f9954 100644
--- a/clang/test/SemaTemplate/concepts.cpp
+++ b/clang/test/SemaTemplate/concepts.cpp
@@ -1658,3 +1658,48 @@ struct {
 void foo() { call(""); }
 
 }
+
+namespace GH170856 {
+
+template <unsigned N, unsigned M> struct symbol_text {
+  consteval symbol_text(const char txt[]) {}
+};
+template <unsigned N> symbol_text(const char (&)[N]) -> symbol_text<1, 1>;
+struct quantity_spec_interface_base {};
+template <symbol_text, auto...> struct named_unit;
+struct quantity_spec_interface : quantity_spec_interface_base {};
+struct : quantity_spec_interface {
+} thermodynamic_temperature;
+
+template <typename T>
+concept QuantitySpec = __is_convertible(T*, quantity_spec_interface_base*);
+template <typename, auto QS>
+concept QuantitySpecOf = QuantitySpec<decltype(QS)>;
+template <typename T, auto QS>
+concept PointOriginFor = QuantitySpecOf<decltype(QS), T::_quantity_spec_>;
+
+template <symbol_text Symbol, auto QS, auto PO>
+struct named_unit<Symbol, QS, PO> {
+  static constexpr auto _point_origin_ = PO;
+};
+template <auto QS> struct absolute_point_origin {
+  static constexpr auto _quantity_spec_ = QS;
+};
+template <auto> struct relative_point_origin {};
+template <class R>
+consteval PointOriginFor<R{}> auto default_point_origin(R) {
+  return R{}._point_origin_;
+}
+template <auto> class quantity_point;
+template <class R> struct point_ {
+  quantity_point<default_point_origin(R{})> operator0();
+};
+template <auto R> point_<decltype(R)> point;
+struct absolute_zero : absolute_point_origin<thermodynamic_temperature> {
+} absolute_zero;
+auto zeroth_kelvin = absolute_zero;
+struct : named_unit<"", thermodynamic_temperature, zeroth_kelvin> {
+} kelvin;
+struct ice_point : relative_point_origin<point<kelvin>> {};
+
+}