diff --git a/flang/lib/semantics/mod-file.cc b/flang/lib/semantics/mod-file.cc
index c422ae8671a5..f703ca151650 100644
--- a/flang/lib/semantics/mod-file.cc
+++ b/flang/lib/semantics/mod-file.cc
@@ -164,6 +164,15 @@ void ModFileWriter::PutSymbol(
               PutLower(typeBindings << "=>", *proc) << '\n';
             }
           },
+          [&](const NamelistDetails &x) {
+            PutLower(decls_ << "namelist/", symbol);
+            char sep = '/';
+            for (const auto *object : x.objects()) {
+              PutLower(decls_ << sep, *object);
+              sep = ',';
+            }
+            decls_ << '\n';
+          },
           [&](const FinalProcDetails &) {
             PutLower(typeBindings << "final::", symbol) << '\n';
           },
@@ -280,6 +289,7 @@ void ModFileWriter::PutUseExtraAttr(
 }
 
 // Collect the symbols of this scope sorted by their original order, not name.
+// Namelists are an exception: they are sorted to the end.
 std::vector<const Symbol *> CollectSymbols(const Scope &scope) {
   std::set<const Symbol *> symbols;  // to prevent duplicates
   std::vector<const Symbol *> sorted;
@@ -293,7 +303,13 @@ std::vector<const Symbol *> CollectSymbols(const Scope &scope) {
     }
   }
   std::sort(sorted.begin(), sorted.end(), [](const Symbol *x, const Symbol *y) {
-    return x->name().begin() < y->name().begin();
+    bool xIsNml{x->has<NamelistDetails>()};
+    bool yIsNml{y->has<NamelistDetails>()};
+    if (xIsNml != yIsNml) {
+      return xIsNml < yIsNml;
+    } else {
+      return x->name().begin() < y->name().begin();
+    }
   });
   return sorted;
 }
diff --git a/flang/lib/semantics/resolve-names.cc b/flang/lib/semantics/resolve-names.cc
index 06a52c02430b..6b6d5fc91102 100644
--- a/flang/lib/semantics/resolve-names.cc
+++ b/flang/lib/semantics/resolve-names.cc
@@ -685,6 +685,8 @@ public:
   bool Pre(const parser::AllocateStmt &);
   void Post(const parser::AllocateStmt &);
   bool Pre(const parser::StructureConstructor &);
+  bool Pre(const parser::NamelistStmt::Group &);
+  bool Pre(const parser::IoControlSpec &);
 
 protected:
   bool BeginDecl();
@@ -3002,6 +3004,49 @@ bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
   return false;
 }
 
+bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
+  if (currScope().kind() == Scope::Kind::Block) {
+    Say("NAMELIST statement is not allowed in a BLOCK construct"_err_en_US);
+    return false;
+  }
+
+  NamelistDetails details;
+  for (const auto &name : std::get<std::list<parser::Name>>(x.t)) {
+    auto *symbol{FindSymbol(name)};
+    if (!symbol) {
+      symbol = &MakeSymbol(name, ObjectEntityDetails{});
+      ApplyImplicitRules(*symbol);
+    } else if (!ConvertToObjectEntity(*symbol)) {
+      SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
+    }
+    details.add_object(*symbol);
+  }
+
+  const auto &groupName{std::get<parser::Name>(x.t)};
+  auto *groupSymbol{FindInScope(currScope(), groupName)};
+  if (!groupSymbol) {
+    groupSymbol = &MakeSymbol(groupName, std::move(details));
+  } else if (groupSymbol->has<NamelistDetails>()) {
+    groupSymbol->get<NamelistDetails>().add_objects(details.objects());
+  } else {
+    SayAlreadyDeclared(groupName, *groupSymbol);
+  }
+  return false;
+}
+
+bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
+  if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
+    auto *symbol{FindSymbol(*name)};
+    if (!symbol) {
+      Say(*name, "Namelist group '%s' not found"_err_en_US);
+    } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
+      SayWithDecl(
+          *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
+    }
+  }
+  return true;
+}
+
 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
   auto *prev{FindSymbol(name)};
   bool implicit{false};
diff --git a/flang/lib/semantics/symbol.cc b/flang/lib/semantics/symbol.cc
index 3b80fe01fec3..1ce87dd00c05 100644
--- a/flang/lib/semantics/symbol.cc
+++ b/flang/lib/semantics/symbol.cc
@@ -152,6 +152,7 @@ std::string DetailsToString(const Details &details) {
           [](const GenericDetails &) { return "Generic"; },
           [](const ProcBindingDetails &) { return "ProcBinding"; },
           [](const GenericBindingDetails &) { return "GenericBinding"; },
+          [](const NamelistDetails &) { return "Namelist"; },
           [](const FinalProcDetails &) { return "FinalProc"; },
           [](const TypeParamDetails &) { return "TypeParam"; },
           [](const MiscDetails &) { return "Misc"; },
@@ -376,6 +377,12 @@ std::ostream &operator<<(std::ostream &os, const Details &details) {
               sep = ',';
             }
           },
+          [&](const NamelistDetails &x) {
+            os << ": ";
+            for (const auto *object : x.objects()) {
+              os << ' ' << object->name();
+            }
+          },
           [&](const FinalProcDetails &) {},
           [&](const TypeParamDetails &x) {
             if (x.type()) {
diff --git a/flang/lib/semantics/symbol.h b/flang/lib/semantics/symbol.h
index ed48301884f9..a798a278e30c 100644
--- a/flang/lib/semantics/symbol.h
+++ b/flang/lib/semantics/symbol.h
@@ -246,6 +246,18 @@ private:
   SymbolList specificProcs_;
 };
 
+class NamelistDetails {
+public:
+  const SymbolList &objects() const { return objects_; }
+  void add_object(const Symbol &object) { objects_.push_back(&object); }
+  void add_objects(const SymbolList &objects) {
+    objects_.insert(objects_.end(), objects.begin(), objects.end());
+  }
+
+private:
+  SymbolList objects_;
+};
+
 class FinalProcDetails {};
 
 class MiscDetails {
@@ -353,8 +365,8 @@ using Details = std::variant<UnknownDetails, MainProgramDetails, ModuleDetails,
     SubprogramDetails, SubprogramNameDetails, EntityDetails,
     ObjectEntityDetails, ProcEntityDetails, AssocEntityDetails,
     DerivedTypeDetails, UseDetails, UseErrorDetails, HostAssocDetails,
-    GenericDetails, ProcBindingDetails, GenericBindingDetails, FinalProcDetails,
-    TypeParamDetails, MiscDetails>;
+    GenericDetails, ProcBindingDetails, GenericBindingDetails, NamelistDetails,
+    FinalProcDetails, TypeParamDetails, MiscDetails>;
 std::ostream &operator<<(std::ostream &, const Details &);
 std::string DetailsToString(const Details &);
 
diff --git a/flang/test/semantics/CMakeLists.txt b/flang/test/semantics/CMakeLists.txt
index eb3d26f33adf..72d591842332 100644
--- a/flang/test/semantics/CMakeLists.txt
+++ b/flang/test/semantics/CMakeLists.txt
@@ -65,6 +65,7 @@ set(ERROR_TESTS
   resolve37.f90
   resolve38.f90
   resolve39.f90
+  resolve40.f90
 )
 
 # These test files have expected symbols in the source
@@ -104,6 +105,7 @@ set(MODFILE_TESTS
   modfile16.f90
   modfile17.f90
   modfile18.f90
+  modfile19.f90
 )
 
 set(LABEL_TESTS
diff --git a/flang/test/semantics/modfile19.f90 b/flang/test/semantics/modfile19.f90
new file mode 100644
index 000000000000..e8e3aa08875e
--- /dev/null
+++ b/flang/test/semantics/modfile19.f90
@@ -0,0 +1,33 @@
+! Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
+!
+! Licensed under the Apache License, Version 2.0 (the "License");
+! you may not use this file except in compliance with the License.
+! You may obtain a copy of the License at
+!
+!     http://www.apache.org/licenses/LICENSE-2.0
+!
+! Unless required by applicable law or agreed to in writing, software
+! distributed under the License is distributed on an "AS IS" BASIS,
+! WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+! See the License for the specific language governing permissions and
+! limitations under the License.
+
+module m
+  implicit complex(8)(z)
+  real :: x
+  namelist /nl1/ x, y
+  namelist /nl2/ y, x
+  namelist /nl1/ i, z
+  complex(8) :: z
+  real :: y
+end
+
+!Expect: m.mod
+!module m
+!  real(4)::x
+!  real(4)::y
+!  integer(4)::i
+!  complex(8)::z
+!  namelist/nl1/x,y,i,z
+!  namelist/nl2/y,x
+!end
diff --git a/flang/test/semantics/resolve40.f90 b/flang/test/semantics/resolve40.f90
new file mode 100644
index 000000000000..806eac8da9be
--- /dev/null
+++ b/flang/test/semantics/resolve40.f90
@@ -0,0 +1,76 @@
+! Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
+!
+! Licensed under the Apache License, Version 2.0 (the "License");
+! you may not use this file except in compliance with the License.
+! You may obtain a copy of the License at
+!
+!     http://www.apache.org/licenses/LICENSE-2.0
+!
+! Unless required by applicable law or agreed to in writing, software
+! distributed under the License is distributed on an "AS IS" BASIS,
+! WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+! See the License for the specific language governing permissions and
+! limitations under the License.
+
+subroutine s1
+  namelist /nl/x
+  block
+    !ERROR: NAMELIST statement is not allowed in a BLOCK construct
+    namelist /nl/y
+  end block
+end
+
+subroutine s2
+  open(12, file='nl.out')
+  !ERROR: Namelist group 'nl' not found
+  write(12, nml=nl)
+end
+
+subroutine s3
+  real :: x
+  open(12, file='nl.out')
+  !ERROR: 'x' is not the name of a namelist group
+  write(12, nml=x)
+end
+
+module m4
+  real :: x
+  namelist /nl/x
+end
+subroutine s4a
+  use m4
+  namelist /nl2/x
+  open(12, file='nl.out')
+  write(12, nml=nl)
+  write(12, nml=nl2)
+end
+subroutine s4b
+  use m4
+  real :: y
+  !ERROR: 'nl' is already declared in this scoping unit
+  namelist /nl/y
+end
+
+subroutine s5
+  namelist /nl/x
+  !ERROR: The type of 'x' has already been implicitly declared
+  integer x
+end
+
+subroutine s6
+  !ERROR: 's6' is not a variable
+  namelist /nl/ s6
+  !ERROR: 'f' is not a variable
+  namelist /nl/ f
+contains
+  integer function f()
+    f = 1
+  end
+end
+
+subroutine s7
+  real x
+  namelist /nl/ x
+  !ERROR: EXTERNAL attribute not allowed on 'x'
+  external x
+end