Index: clang/lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -3621,15 +3621,6 @@
   D = getCanonicalParmVarDecl(D);
   llvm::PointerUnion<Decl *, DeclArgumentPack *> &Stored = LocalDecls[D];
   if (Stored.isNull()) {
-#ifndef NDEBUG
-    // It should not be present in any surrounding scope either.
-    LocalInstantiationScope *Current = this;
-    while (Current->CombineWithOuterScope && Current->Outer) {
-      Current = Current->Outer;
-      assert(Current->LocalDecls.find(D) == Current->LocalDecls.end() &&
-             "Instantiated local in inner and outer scopes");
-    }
-#endif
     Stored = Inst;
   } else if (DeclArgumentPack *Pack = Stored.dyn_cast<DeclArgumentPack *>()) {
     Pack->push_back(cast<VarDecl>(Inst));
@@ -3646,14 +3637,6 @@
 }
 
 void LocalInstantiationScope::MakeInstantiatedLocalArgPack(const Decl *D) {
-#ifndef NDEBUG
-  // This should be the first time we've been told about this decl.
-  for (LocalInstantiationScope *Current = this;
-       Current && Current->CombineWithOuterScope; Current = Current->Outer)
-    assert(Current->LocalDecls.find(D) == Current->LocalDecls.end() &&
-           "Creating local pack after instantiation of local");
-#endif
-
   D = getCanonicalParmVarDecl(D);
   llvm::PointerUnion<Decl *, DeclArgumentPack *> &Stored = LocalDecls[D];
   DeclArgumentPack *Pack = new DeclArgumentPack;
Index: clang/test/SemaCXX/recursive-lambda.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/recursive-lambda.cpp
@@ -0,0 +1,30 @@
+// RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify %s
+
+// expected-no-diagnostics
+
+// Check recursive instantiation of lambda does not cause assertion.
+
+template <unsigned v>
+struct Number
+{
+   static constexpr unsigned value = v;
+};
+
+template <unsigned IBegin = 0,
+          unsigned IEnd = 1>
+constexpr auto fun1(Number<IBegin> = Number<0>{}, Number<IEnd>  = Number<1>{})
+{
+  auto f = [&](auto fs, auto i) {
+    if constexpr(i.value > 0)
+    {
+      return fs(fs, Number<IBegin>{});
+    }
+  };
+
+  return f(f, Number<IEnd>{});
+}
+
+
+void fun2() {
+  fun1();
+}