Index: lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- lib/Sema/SemaTemplateInstantiate.cpp
+++ lib/Sema/SemaTemplateInstantiate.cpp
@@ -2913,6 +2913,9 @@
   // error recovery.
   if (isa<EnumDecl>(D))
     return nullptr;
+  if (const VarDecl *VD = dyn_cast<VarDecl>(D))
+    if (VD->isInitCapture())
+      return nullptr;
 
   // If we didn't find the decl, then we either have a sema bug, or we have a
   // forward reference to a label declaration.  Return null to indicate that
Index: lib/Sema/SemaTemplateInstantiateDecl.cpp
===================================================================
--- lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -4962,6 +4962,14 @@
       return cast<TypeDecl>(Inst);
     }
 
+    // If the variable is in InitCapture and variable types are of type
+    // mentioned in the above comment (the comment starting as "Normally
+    // this function...") then its existance won't be known so we have to
+    // make an exclusion for them.
+    if (const VarDecl *VD = dyn_cast<VarDecl>(D))
+      if (VD->isInitCapture())
+        return nullptr;
+
     // If we didn't find the decl, then we must have a label decl that hasn't
     // been found yet.  Lazily instantiate it and return it now.
     assert(isa<LabelDecl>(D));
Index: test/SemaCXX/lambda-init-capture-vardefine.cpp
===================================================================
--- /dev/null
+++ test/SemaCXX/lambda-init-capture-vardefine.cpp
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -std=c++14  -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c++17  -fsyntax-only -verify %s
+// expected-no-diagnostics
+
+template <typename...> using a = void;
+template <int b> struct c { static const int d = b; };
+template <class, class = a<>> struct e : c<true> {};
+template <class g> g h(int);
+template <class g> decltype(h<g>(0)) i;
+template <class j> struct e<j, a<decltype(i<j>())>>;
+template <typename k> auto func(k &&);
+template <int> struct l {
+  template <typename k> static auto n(k o) {
+    return [f{o}](auto) { func([](auto...) -> decltype(f) {}); };
+  }
+};
+template <typename k> auto func(k &&o) { return l<e<decltype(o)>::d>::n(o); }
+int main(void) {
+  auto f = [](auto) {};
+  func(f)(1);
+}