diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
@@ -638,6 +638,8 @@ ExprResult Parser::ParseCXXIdExpression(bool isAddressOfOperand) {
 ///
 ///       lambda-expression:
 ///         lambda-introducer lambda-declarator[opt] compound-statement
+///         lambda-introducer '<' template-parameter-list '>'
+///             lambda-declarator[opt] compound-statement
 ///
 ///       lambda-introducer:
 ///         '[' lambda-capture[opt] ']'
@@ -1121,6 +1123,33 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
               << A.getName()->getName();
   };
 
+  // FIXME: Consider allowing this as an extension for GCC compatibiblity.
+  const bool HasExplicitTemplateParams = Tok.is(tok::less);
+  ParseScope TemplateParamScope(this, Scope::TemplateParamScope,
+                                /*EnteredScope=*/HasExplicitTemplateParams);
+  if (HasExplicitTemplateParams) {
+    Diag(Tok, getLangOpts().CPlusPlus2a
+                  ? diag::warn_cxx17_compat_lambda_template_parameter_list
+                  : diag::ext_lambda_template_parameter_list);
+
+    SmallVector<NamedDecl*, 4> TemplateParams;
+    SourceLocation LAngleLoc, RAngleLoc;
+    if (ParseTemplateParameters(CurTemplateDepthTracker.getDepth(),
+                                TemplateParams, LAngleLoc, RAngleLoc)) {
+      Actions.ActOnLambdaError(LambdaBeginLoc, getCurScope());
+      return ExprError();
+    }
+
+    if (TemplateParams.empty()) {
+      Diag(RAngleLoc,
+           diag::err_lambda_template_parameter_list_empty);
+    } else {
+      Actions.ActOnLambdaExplicitTemplateParameterList(
+          LAngleLoc, TemplateParams, RAngleLoc);
+      ++CurTemplateDepthTracker;
+    }
+  }
+
   TypeResult TrailingReturnType;
   if (Tok.is(tok::l_paren)) {
     ParseScope PrototypeScope(this,
@@ -1137,13 +1166,20 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
     SourceLocation EllipsisLoc;
 
     if (Tok.isNot(tok::r_paren)) {
-      Actions.RecordParsingTemplateParameterDepth(TemplateParameterDepth);
+      Actions.RecordParsingTemplateParameterDepth(
+          CurTemplateDepthTracker.getOriginalDepth());
+
       ParseParameterDeclarationClause(D, Attr, ParamInfo, EllipsisLoc);
+
       // For a generic lambda, each 'auto' within the parameter declaration
       // clause creates a template type parameter, so increment the depth.
+      // If we've parsed any explicit template parameters, then the depth will
+      // have already been incremented. So we make sure that at most a single
+      // depth level is added.
       if (Actions.getCurGenericLambda())
-        ++CurTemplateDepthTracker;
+        CurTemplateDepthTracker.setAddedDepth(1);
     }
+
     T.consumeClose();
     SourceLocation RParenLoc = T.getCloseLocation();
     SourceLocation DeclEndLoc = RParenLoc;
@@ -1298,6 +1334,7 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
 
   StmtResult Stmt(ParseCompoundStatementBody());
   BodyScope.Exit();
+  TemplateParamScope.Exit();
 
   if (!Stmt.isInvalid() && !TrailingReturnType.isInvalid())
     return Actions.ActOnLambdaExpr(LambdaBeginLoc, Stmt.get(), getCurScope());

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
@@ -1793,7 +1793,7 @@ LambdaScopeInfo *Sema::getCurLambda(bool IgnoreNonLambdaCapturingScope) {
 // an associated template parameter list.
 LambdaScopeInfo *Sema::getCurGenericLambda() {
   if (LambdaScopeInfo *LSI =  getCurLambda()) {
-    return (LSI->AutoTemplateParams.size() ||
+    return (LSI->TemplateParams.size() ||
                     LSI->GLTemplateParameterList) ? LSI : nullptr;
   }
   return nullptr;

diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
@@ -20,6 +20,7 @@
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/SemaLambda.h"
+#include "llvm/ADT/STLExtras.h"
 using namespace clang;
 using namespace sema;
 
@@ -225,19 +226,14 @@ Optional<unsigned> clang::getStackIndexOfNearestEnclosingCaptureCapableLambda(
 
 static inline TemplateParameterList *
 getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI, Sema &SemaRef) {
-  if (LSI->GLTemplateParameterList)
-    return LSI->GLTemplateParameterList;
-
-  if (!LSI->AutoTemplateParams.empty()) {
-    SourceRange IntroRange = LSI->IntroducerRange;
-    SourceLocation LAngleLoc = IntroRange.getBegin();
-    SourceLocation RAngleLoc = IntroRange.getEnd();
+  if (!LSI->GLTemplateParameterList && !LSI->TemplateParams.empty()) {
     LSI->GLTemplateParameterList = TemplateParameterList::Create(
         SemaRef.Context,
-        /*Template kw loc*/ SourceLocation(), LAngleLoc,
-        llvm::makeArrayRef((NamedDecl *const *)LSI->AutoTemplateParams.data(),
-                           LSI->AutoTemplateParams.size()),
-        RAngleLoc, nullptr);
+        /*Template kw loc*/ SourceLocation(),
+        /*L angle loc*/ LSI->ExplicitTemplateParamsRange.getBegin(),
+        LSI->TemplateParams,
+        /*R angle loc*/LSI->ExplicitTemplateParamsRange.getEnd(),
+        nullptr);
   }
   return LSI->GLTemplateParameterList;
 }
@@ -492,6 +488,23 @@ void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
   LSI->finishedExplicitCaptures();
 }
 
+void Sema::ActOnLambdaExplicitTemplateParameterList(SourceLocation LAngleLoc,
+                                                    ArrayRef<NamedDecl *> TParams,
+                                                    SourceLocation RAngleLoc) {
+  LambdaScopeInfo *LSI = getCurLambda();
+  assert(LSI && "Expected a lambda scope");
+  assert(LSI->NumExplicitTemplateParams == 0 &&
+         "Already acted on explicit template parameters");
+  assert(LSI->TemplateParams.empty() &&
+         "Explicit template parameters should come "
+         "before invented (auto) ones");
+  assert(!TParams.empty() &&
+         "No template parameters to act on");
+  LSI->TemplateParams.append(TParams.begin(), TParams.end());
+  LSI->NumExplicitTemplateParams = TParams.size();
+  LSI->ExplicitTemplateParamsRange = {LAngleLoc, RAngleLoc};
+}
+
 void Sema::addLambdaParameters(
     ArrayRef<LambdaIntroducer::LambdaCapture> Captures,
     CXXMethodDecl *CallOperator, Scope *CurScope) {
@@ -832,17 +845,23 @@ FieldDecl *Sema::buildInitCaptureField(LambdaScopeInfo *LSI, VarDecl *Var) {
 void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
                                         Declarator &ParamInfo,
                                         Scope *CurScope) {
-  // Determine if we're within a context where we know that the lambda will
-  // be dependent, because there are template parameters in scope.
-  bool KnownDependent = false;
   LambdaScopeInfo *const LSI = getCurLambda();
   assert(LSI && "LambdaScopeInfo should be on stack!");
 
-  // The lambda-expression's closure type might be dependent even if its
-  // semantic context isn't, if it appears within a default argument of a
-  // function template.
-  if (CurScope->getTemplateParamParent())
-    KnownDependent = true;
+  // Determine if we're within a context where we know that the lambda will
+  // be dependent, because there are template parameters in scope.
+  bool KnownDependent;
+  if (LSI->NumExplicitTemplateParams > 0) {
+    auto *TemplateParamScope = CurScope->getTemplateParamParent();
+    assert(TemplateParamScope &&
+           "Lambda with explicit template param list should establish a "
+           "template param scope");
+    assert(TemplateParamScope->getParent());
+    KnownDependent = TemplateParamScope->getParent()
+                                       ->getTemplateParamParent() != nullptr;
+  } else {
+    KnownDependent = CurScope->getTemplateParamParent() != nullptr;
+  }
 
   // Determine the signature of the call operator.
   TypeSourceInfo *MethodTyInfo;

diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
@@ -2935,7 +2935,7 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
         sema::LambdaScopeInfo *LSI = SemaRef.getCurLambda();
         assert(LSI && "No LambdaScopeInfo on the stack!");
         const unsigned TemplateParameterDepth = LSI->AutoTemplateParameterDepth;
-        const unsigned AutoParameterPosition = LSI->AutoTemplateParams.size();
+        const unsigned AutoParameterPosition = LSI->TemplateParams.size();
         const bool IsParameterPack = D.hasEllipsis();
 
         // Create the TemplateTypeParmDecl here to retrieve the corresponding
@@ -2947,7 +2947,8 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
                 /*KeyLoc*/ SourceLocation(), /*NameLoc*/ D.getBeginLoc(),
                 TemplateParameterDepth, AutoParameterPosition,
                 /*Identifier*/ nullptr, false, IsParameterPack);
-        LSI->AutoTemplateParams.push_back(CorrespondingTemplateParam);
+        CorrespondingTemplateParam->setImplicit();
+        LSI->TemplateParams.push_back(CorrespondingTemplateParam);
         // Replace the 'auto' in the function parameter with this invented
         // template type parameter.
         // FIXME: Retain some type sugar to indicate that this was written

diff --git a/clang/test/CXX/temp/temp.decls/temp.variadic/p4.cpp b/clang/test/CXX/temp/temp.decls/temp.variadic/p4.cpp
@@ -213,8 +213,10 @@ namespace PackExpansionWithinLambda {
       };
 #endif
 
+#if __cplusplus > 201703L
       //    - in a template parameter pack that is a pack expansion
-      // FIXME: We do not support any way to reach this case yet.
+      swallow([]<T *...v, template<T *> typename ...W>(W<v> ...wv) { });
+#endif
 
       //    - in an initializer-list
       int arr[] = {T().x...};
@@ -279,11 +281,6 @@ namespace PackExpansionWithinLambda {
   struct T { int x; using U = int; };
   void g() { f<T>(1, 2, 3); }
 
-  template<typename ...T, typename ...U> void pack_in_lambda(U ...u) { // expected-note {{here}}
-    // FIXME: Move this test into 'f' above once we support this syntax.
-    []<T *...v, template<T *> typename ...U>(U<v> ...uv) {}; // expected-error {{expected body of lambda}} expected-error {{does not refer to a value}}
-  }
-
   template<typename ...T> void pack_expand_attr() {
     // FIXME: Move this test into 'f' above once we support this.
     [[gnu::aligned(alignof(T))...]] int x; // expected-error {{cannot be used as an attribute pack}} expected-error {{unexpanded}}

diff --git a/clang/test/CodeGenCXX/mangle-lambda-explicit-template-params.cpp b/clang/test/CodeGenCXX/mangle-lambda-explicit-template-params.cpp
@@ -0,0 +1,34 @@
+// RUN: %clang_cc1 -std=c++2a -triple %itanium_abi_triple -emit-llvm -o - %s -w | FileCheck %s
+
+template<class, int, class>
+struct DummyType { };
+
+inline void inline_func() {
+  // CHECK: UlvE
+  []{}();
+
+  // CHECK: UlTyvE
+  []<class>{}.operator()<int>();
+
+  // CHECK: UlTyT_E
+  []<class T>(T){}(1);
+
+  // CHECK: UlTyTyT_T0_E
+  []<class T1, class T2>(T1, T2){}(1, 2);
+
+  // CHECK: UlTyTyT0_T_E
+  []<class T1, class T2>(T2, T1){}(2, 1);
+
+  // CHECK: UlTniTyTnjT0_E
+  []<int I, class T, unsigned U>(T){}.operator()<1, int, 2>(3);
+
+  // CHECK: UlTyTtTyTniTyETniTyvE
+  []<class,
+     template<class, int, class> class,
+     int,
+     class>{}.operator()<unsigned, DummyType, 5, int>();
+}
+
+void call_inline_func() {
+  inline_func();
+}
diff --git a/clang/test/Index/print-display-names.cpp b/clang/test/Index/print-display-names.cpp
@@ -20,7 +20,7 @@ template<> void g<int>(ClassTmpl<int, int>);
 // DISPLAY_NAME: print-display-names.cpp:13:17: FunctionDecl=g<>(ClassTmpl<int, int>):13:17 [Specialization of g:11:6]
 
 // RUN: env CINDEXTEST_PRINTINGPOLICY_TERSEOUTPUT=1 c-index-test -test-load-source all-pretty %s | FileCheck %s --check-prefix=PRETTY
-// PRETTY: print-display-names.cpp:2:7: ClassTemplate=template <typename T, typename > class ClassTmpl {}:2:7 (Definition) Extent=[1:1 - 2:20]
+// PRETTY: print-display-names.cpp:2:7: ClassTemplate=template <typename T, typename> class ClassTmpl {}:2:7 (Definition) Extent=[1:1 - 2:20]
 // PRETTY: print-display-names.cpp:4:13: TypedefDecl=typedef int Integer:4:13 (Definition) Extent=[4:1 - 4:20]
 // PRETTY: print-display-names.cpp:6:16: ClassDecl=template<> class ClassTmpl<int, int> {}:6:16 (Definition) [Specialization of ClassTmpl:2:7] Extent=[6:1 - 6:43]
 // PRETTY: print-display-names.cpp:8:6: FunctionDecl=void f(ClassTmpl<float, Integer> p):8:6 Extent=[8:1 - 8:36]

diff --git a/clang/test/PCH/cxx11-lambdas.mm b/clang/test/PCH/cxx11-lambdas.mm
@@ -54,7 +54,7 @@ int add(int x, int y) {
 }
 
 // CHECK-PRINT: inline int add_int_slowly_twice 
-// CHECK-PRINT: lambda = [&] (int z)
+// CHECK-PRINT: lambda = [&](int z)
 
 // CHECK-PRINT: init_capture
 // CHECK-PRINT: [&, x(t)]

diff --git a/clang/test/PCH/cxx1y-lambdas.mm b/clang/test/PCH/cxx1y-lambdas.mm
@@ -50,7 +50,7 @@ int add(int x, int y) {
 }
 
 // CHECK-PRINT: inline int add_int_slowly_twice 
-// CHECK-PRINT: lambda = [] (type-parameter-0-0 z
+// CHECK-PRINT: lambda = [](auto z
 
 // CHECK-PRINT: init_capture
 // CHECK-PRINT: [&, x(t)]

diff --git a/clang/test/PCH/cxx2a-template-lambdas.cpp b/clang/test/PCH/cxx2a-template-lambdas.cpp
@@ -0,0 +1,42 @@
+// RUN: %clang_cc1 -std=c++2a -emit-pch %s -o %t
+// RUN: %clang_cc1 -std=c++2a -include-pch %t -verify %s
+
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
+
+auto l1 = []<int I>() constexpr -> int {
+    return I;
+};
+
+auto l2 = []<auto I>() constexpr -> decltype(I) {
+    return I;
+};
+
+auto l3 = []<class T>(auto i) constexpr -> T {
+  return T(i);
+};
+
+auto l4 = []<template<class> class T, class U>(T<U>, auto i) constexpr -> U {
+  return U(i);
+};
+
+#else /*included pch*/
+
+static_assert(l1.operator()<5>() == 5);
+static_assert(l1.operator()<6>() == 6);
+
+static_assert(l2.operator()<7>() == 7);
+static_assert(l2.operator()<nullptr>() == nullptr);
+
+static_assert(l3.operator()<int>(8.4) == 8);
+static_assert(l3.operator()<int>(9.9) == 9);
+
+template<typename T>
+struct DummyTemplate { };
+
+static_assert(l4(DummyTemplate<float>(), 12) == 12.0);
+static_assert(l4(DummyTemplate<int>(), 19.8) == 19);
+
+#endif // HEADER
diff --git a/clang/test/Parser/cxx2a-template-lambdas.cpp b/clang/test/Parser/cxx2a-template-lambdas.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -std=c++2a %s -verify
+
+auto L0 = []<> { }; //expected-error {{cannot be empty}}
+
+auto L1 = []<typename T1, typename T2> { };
+auto L2 = []<typename T1, typename T2>(T1 arg1, T2 arg2) -> T1 { };
+auto L3 = []<typename T>(auto arg) { T t; };
+auto L4 = []<int I>() { };
diff --git a/clang/test/SemaCXX/cxx2a-template-lambdas.cpp b/clang/test/SemaCXX/cxx2a-template-lambdas.cpp
@@ -0,0 +1,45 @@
+// RUN: %clang_cc1 -std=c++2a -verify %s
+
+template<typename, typename>
+constexpr bool is_same = false;
+
+template<typename T>
+constexpr bool is_same<T, T> = true;
+
+template<typename T>
+struct DummyTemplate { };
+
+void func() {
+  auto L0 = []<typename T>(T arg) {
+    static_assert(is_same<T, int>); // expected-error {{static_assert failed}}
+  };
+  L0(0);
+  L0(0.0); // expected-note {{in instantiation}}
+
+  auto L1 = []<int I> {
+    static_assert(I == 5); // expected-error {{static_assert failed}}
+  };
+  L1.operator()<5>();
+  L1.operator()<6>(); // expected-note {{in instantiation}}
+
+  auto L2 = []<template<typename> class T, class U>(T<U> &&arg) {
+    static_assert(is_same<T<U>, DummyTemplate<float>>); // // expected-error {{static_assert failed}}
+  };
+  L2(DummyTemplate<float>());
+  L2(DummyTemplate<double>()); // expected-note {{in instantiation}}
+}
+
+template<typename T> // expected-note {{declared here}}
+struct ShadowMe {
+  void member_func() {
+    auto L = []<typename T> { }; // expected-error {{'T' shadows template parameter}}
+  }
+};
+
+template<typename T>
+constexpr T outer() {
+  return []<T x>() { return x; }.template operator()<123>(); // expected-error {{no matching member function}} \
+                                                                expected-note {{candidate template ignored}}
+}
+static_assert(outer<int>() == 123);
+template int *outer<int *>(); // expected-note {{in instantiation}}
diff --git a/clang/unittests/AST/StmtPrinterTest.cpp b/clang/unittests/AST/StmtPrinterTest.cpp
@@ -157,6 +157,43 @@ TEST(StmtPrinter, TestCXXConversionDeclExplicit) {
     // WRONG; Should be: (a & b).operator void *()
 }
 
+TEST(StmtPrinter, TestCXXLamda) {
+  ASSERT_TRUE(PrintedStmtCXXMatches(StdVer::CXX11,
+    "void A() {"
+    "  auto l = [] { };"
+    "}",
+    lambdaExpr(anything()).bind("id"),
+    "[] {\n"
+    "}"));
+
+  ASSERT_TRUE(PrintedStmtCXXMatches(StdVer::CXX11,
+    "void A() {"
+    "  int a = 0, b = 1;"
+    "  auto l = [a,b](int c, float d) { };"
+    "}",
+    lambdaExpr(anything()).bind("id"),
+    "[a, b](int c, float d) {\n"
+    "}"));
+
+  ASSERT_TRUE(PrintedStmtCXXMatches(StdVer::CXX14,
+    "void A() {"
+    "  auto l = [](auto a, int b, auto c, int, auto) { };"
+    "}",
+    lambdaExpr(anything()).bind("id"),
+    "[](auto a, int b, auto c, int, auto) {\n"
+    "}"));
+
+  ASSERT_TRUE(PrintedStmtCXXMatches(StdVer::CXX2a,
+    "void A() {"
+    "  auto l = []<typename T1, class T2, int I,"
+    "              template<class, typename> class T3>"
+    "           (int a, auto, int, auto d) { };"
+    "}",
+    lambdaExpr(anything()).bind("id"),
+    "[]<typename T1, class T2, int I, template <class, typename> class T3>(int a, auto, int, auto d) {\n"
+    "}"));
+}
+
 TEST(StmtPrinter, TestNoImplicitBases) {
   const char *CPPSource = R"(
 class A {

diff --git a/clang/unittests/Tooling/RecursiveASTVisitorTests/LambdaTemplateParams.cpp b/clang/unittests/Tooling/RecursiveASTVisitorTests/LambdaTemplateParams.cpp
@@ -0,0 +1,53 @@
+//===- unittest/Tooling/RecursiveASTVisitorTests/LambdaTemplateParams.cpp -===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "TestVisitor.h"
+
+using namespace clang;
+
+namespace {
+
+// Matches (optional) explicit template parameters.
+class LambdaTemplateParametersVisitor
+  : public ExpectedLocationVisitor<LambdaTemplateParametersVisitor> {
+public:
+  bool shouldVisitImplicitCode() const { return false; }
+
+  bool VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
+    EXPECT_FALSE(D->isImplicit());
+    Match(D->getName(), D->getLocStart());
+    return true;
+  }
+
+  bool VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
+    EXPECT_FALSE(D->isImplicit());
+    Match(D->getName(), D->getLocStart());
+    return true;
+  }
+
+  bool VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D) {
+    EXPECT_FALSE(D->isImplicit());
+    Match(D->getName(), D->getLocStart());
+    return true;
+  }
+};
+
+TEST(RecursiveASTVisitor, VisitsLambdaExplicitTemplateParameters) {
+  LambdaTemplateParametersVisitor Visitor;
+  Visitor.ExpectMatch("T",  2, 15);
+  Visitor.ExpectMatch("I",  2, 24);
+  Visitor.ExpectMatch("TT", 2, 31);
+  EXPECT_TRUE(Visitor.runOver(
+      "void f() { \n"
+      "  auto l = []<class T, int I, template<class> class TT>(auto p) { }; \n"
+      "}",
+      LambdaTemplateParametersVisitor::Lang_CXX2a));
+}
+
+} // end anonymous namespace
diff --git a/clang/www/cxx_status.html b/clang/www/cxx_status.html
@@ -868,7 +868,7 @@ <h2 id="cxx20">C++2a implementation status</h2>
     <tr>
       <td><i>template-parameter-list</i> for generic lambdas</td>
       <td><a href="http://wg21.link/p0428r2">P0428R2</a></td>
-      <td class="none" align="center">No</td>
+      <td class="svn" align="center">SVN</td>
     </tr>
     <tr id="p0734">
       <td rowspan="4">Concepts</td>