diff --git a/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPIChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPIChecker.cpp
@@ -0,0 +1,190 @@
+//===-- MPIChecker.cpp - Checker Entry Point Class --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file defines the main class of MPI-Checker which serves as an entry
+/// point. It is created once for each translation unit analysed.
+/// The checker defines path-sensitive checks, to verify correct usage of the
+/// MPI API.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MPIChecker.h"
+#include "../ClangSACheckers.h"
+
+namespace clang {
+namespace ento {
+namespace mpi {
+
+void MPIChecker::checkDoubleNonblocking(const CallEvent &PreCallEvent,
+                                        CheckerContext &Ctx) const {
+  if (!FuncClassifier->isNonBlockingType(PreCallEvent.getCalleeIdentifier())) {
+    return;
+  }
+  const MemRegion *const MR =
+      PreCallEvent.getArgSVal(PreCallEvent.getNumArgs() - 1).getAsRegion();
+  if (!MR)
+    return;
+  const ElementRegion *const ER = dyn_cast<ElementRegion>(MR);
+
+  // The region must be typed, in order to reason about it.
+  if (!isa<TypedRegion>(MR) || (ER && !isa<TypedRegion>(ER->getSuperRegion())))
+    return;
+
+  ProgramStateRef State = Ctx.getState();
+  const Request *const Req = State->get<RequestMap>(MR);
+
+  // double nonblocking detected
+  if (Req && Req->CurrentState == Request::State::Nonblocking) {
+    ExplodedNode *ErrorNode = Ctx.generateNonFatalErrorNode();
+    BReporter->reportDoubleNonblocking(PreCallEvent, *Req, MR, ErrorNode);
+    Ctx.addTransition(ErrorNode->getState(), ErrorNode);
+  }
+  // no error
+  else {
+    State = State->set<RequestMap>(MR, Request::State::Nonblocking);
+    Ctx.addTransition(State);
+  }
+}
+
+void MPIChecker::checkUnmatchedWaits(const CallEvent &PreCallEvent,
+                                     CheckerContext &Ctx) const {
+  if (!FuncClassifier->isWaitType(PreCallEvent.getCalleeIdentifier()))
+    return;
+  const MemRegion *const MR = topRegionUsedByWait(PreCallEvent);
+  if (!MR)
+    return;
+  const ElementRegion *const ER = dyn_cast<ElementRegion>(MR);
+
+  // The region must be typed, in order to reason about it.
+  if (!isa<TypedRegion>(MR) || (ER && !isa<TypedRegion>(ER->getSuperRegion())))
+    return;
+
+  llvm::SmallVector<const MemRegion *, 2> ReqRegions;
+  allRegionsUsedByWait(ReqRegions, MR, PreCallEvent, Ctx);
+  if (ReqRegions.empty())
+    return;
+
+  ProgramStateRef State = Ctx.getState();
+  static CheckerProgramPointTag Tag("MPI-Checker", "UnmatchedWait");
+  ExplodedNode *ErrorNode{nullptr};
+
+  // Check all request regions used by the wait function.
+  for (const auto &ReqRegion : ReqRegions) {
+    const Request *const Req = State->get<RequestMap>(ReqRegion);
+    State = State->set<RequestMap>(ReqRegion, Request::State::Wait);
+    if (!Req) {
+      if (!ErrorNode) {
+        ErrorNode = Ctx.generateNonFatalErrorNode(State, &Tag);
+        State = ErrorNode->getState();
+      }
+      // A wait has no matching nonblocking call.
+      BReporter->reportUnmatchedWait(PreCallEvent, ReqRegion, ErrorNode);
+    }
+  }
+
+  if (!ErrorNode) {
+    Ctx.addTransition(State);
+  } else {
+    Ctx.addTransition(State, ErrorNode);
+  }
+}
+
+void MPIChecker::checkMissingWaits(SymbolReaper &SymReaper,
+                                   CheckerContext &Ctx) const {
+  if (!SymReaper.hasDeadSymbols())
+    return;
+
+  ProgramStateRef State = Ctx.getState();
+  const auto &Requests = State->get<RequestMap>();
+  if (Requests.isEmpty())
+    return;
+
+  static CheckerProgramPointTag Tag("MPI-Checker", "MissingWait");
+  ExplodedNode *ErrorNode{nullptr};
+
+  auto ReqMap = State->get<RequestMap>();
+  for (const auto &Req : ReqMap) {
+    if (!SymReaper.isLiveRegion(Req.first)) {
+      if (Req.second.CurrentState == Request::State::Nonblocking) {
+
+        if (!ErrorNode) {
+          ErrorNode = Ctx.generateNonFatalErrorNode(State, &Tag);
+          State = ErrorNode->getState();
+        }
+        BReporter->reportMissingWait(Req.second, Req.first, ErrorNode);
+      }
+      State = State->remove<RequestMap>(Req.first);
+    }
+  }
+
+  // Transition to update the state regarding removed requests.
+  if (!ErrorNode) {
+    Ctx.addTransition(State);
+  } else {
+    Ctx.addTransition(State, ErrorNode);
+  }
+}
+
+const MemRegion *MPIChecker::topRegionUsedByWait(const CallEvent &CE) const {
+
+  if (FuncClassifier->isMPI_Wait(CE.getCalleeIdentifier())) {
+    return CE.getArgSVal(0).getAsRegion();
+  } else if (FuncClassifier->isMPI_Waitall(CE.getCalleeIdentifier())) {
+    return CE.getArgSVal(1).getAsRegion();
+  } else {
+    return (const MemRegion *)nullptr;
+  }
+}
+
+void MPIChecker::allRegionsUsedByWait(
+    llvm::SmallVector<const MemRegion *, 2> &ReqRegions,
+    const MemRegion *const MR, const CallEvent &CE, CheckerContext &Ctx) const {
+
+  MemRegionManager *const RegionManager = MR->getMemRegionManager();
+
+  if (FuncClassifier->isMPI_Waitall(CE.getCalleeIdentifier())) {
+    const MemRegion *SuperRegion{nullptr};
+    if (const ElementRegion *const ER = MR->getAs<ElementRegion>()) {
+      SuperRegion = ER->getSuperRegion();
+    }
+
+    // A single request is passed to MPI_Waitall.
+    if (!SuperRegion) {
+      ReqRegions.push_back(MR);
+      return;
+    }
+
+    const auto &Size = Ctx.getStoreManager().getSizeInElements(
+        Ctx.getState(), SuperRegion,
+        CE.getArgExpr(1)->getType()->getPointeeType());
+    const llvm::APSInt &ArrSize = Size.getAs<nonloc::ConcreteInt>()->getValue();
+
+    for (size_t i = 0; i < ArrSize; ++i) {
+      const NonLoc Idx = Ctx.getSValBuilder().makeArrayIndex(i);
+
+      const ElementRegion *const ER = RegionManager->getElementRegion(
+          CE.getArgExpr(1)->getType()->getPointeeType(), Idx, SuperRegion,
+          Ctx.getASTContext());
+
+      ReqRegions.push_back(ER->getAs<MemRegion>());
+    }
+  } else if (FuncClassifier->isMPI_Wait(CE.getCalleeIdentifier())) {
+    ReqRegions.push_back(MR);
+  }
+}
+
+} // end of namespace: mpi
+} // end of namespace: ento
+} // end of namespace: clang
+
+// Registers the checker for static analysis.
+void clang::ento::registerMPIChecker(CheckerManager &MGR) {
+  MGR.registerChecker<clang::ento::mpi::MPIChecker>();
+}
diff --git a/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPIChecker.h b/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPIChecker.h
@@ -0,0 +1,110 @@
+//===-- MPIChecker.h - Verify MPI API usage- --------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file defines the main class of MPI-Checker which serves as an entry
+/// point. It is created once for each translation unit analysed.
+/// The checker defines path-sensitive checks, to verify correct usage of the
+/// MPI API.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_STATICANALYZER_CHECKERS_MPICHECKER_MPICHECKER_H
+#define LLVM_CLANG_LIB_STATICANALYZER_CHECKERS_MPICHECKER_MPICHECKER_H
+
+#include "MPIBugReporter.h"
+#include "MPIFunctionClassifier.h"
+#include "MPITypes.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+
+namespace clang {
+namespace ento {
+namespace mpi {
+
+class MPIChecker : public Checker<check::PreCall, check::DeadSymbols> {
+public:
+  // path-sensitive callbacks
+  void checkPreCall(const CallEvent &CE, CheckerContext &Ctx) const {
+    dynamicInit(Ctx);
+    checkUnmatchedWaits(CE, Ctx);
+    checkDoubleNonblocking(CE, Ctx);
+  }
+
+  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &Ctx) const {
+    dynamicInit(Ctx);
+    checkMissingWaits(SymReaper, Ctx);
+  }
+
+  void dynamicInit(CheckerContext &Ctx) const {
+    if (IsInitialized)
+      return;
+    const_cast<std::unique_ptr<MPIFunctionClassifier> &>(FuncClassifier)
+        .reset(new MPIFunctionClassifier{Ctx.getAnalysisManager()});
+
+    const_cast<std::unique_ptr<MPIBugReporter> &>(BReporter).reset(
+        new MPIBugReporter{Ctx.getBugReporter(), *this, *FuncClassifier});
+
+    const_cast<bool &>(IsInitialized) = true;
+  }
+
+  /// Checks if a request is used by nonblocking calls multiple times
+  /// in sequence without intermediate wait. The check contains a guard,
+  /// in order to only inspect nonblocking functions.
+  ///
+  /// \param PreCallEvent MPI call to verify
+  void checkDoubleNonblocking(const clang::ento::CallEvent &PreCallEvent,
+                              clang::ento::CheckerContext &Ctx) const;
+
+  /// Checks if a request is used by a wait multiple times in sequence without
+  /// intermediate nonblocking call or if the request used by the wait
+  /// function was not used at all before. The check contains a guard,
+  /// in order to only inspect wait functions.
+  ///
+  /// \param PreCallEvent MPI call to verify
+  void checkUnmatchedWaits(const clang::ento::CallEvent &PreCallEvent,
+                           clang::ento::CheckerContext &Ctx) const;
+
+  /// Check if a nonblocking call is not matched by a wait.
+  /// If a memory region is not alive and the last function using the
+  /// request was a nonblocking call, this is rated as a missing wait.
+  void checkMissingWaits(clang::ento::SymbolReaper &SymReaper,
+                         clang::ento::CheckerContext &Ctx) const;
+
+private:
+  /// Collects all memory regions of a request(array) used by a wait
+  /// function. If the wait function uses a single request, this is a single
+  /// region. For wait functions using multiple requests, multiple regions
+  /// representing elements in the array are collected.
+  ///
+  /// \param ReqRegions vector the regions get pushed into
+  /// \param MR top most region to iterate
+  /// \param CE MPI wait call using the request(s)
+  void allRegionsUsedByWait(
+      llvm::SmallVector<const clang::ento::MemRegion *, 2> &ReqRegions,
+      const clang::ento::MemRegion *const MR, const clang::ento::CallEvent &CE,
+      clang::ento::CheckerContext &Ctx) const;
+
+  /// Returns the memory region used by a wait function.
+  /// Distinguishes between MPI_Wait and MPI_Waitall.
+  ///
+  /// \param CE MPI wait call
+  const clang::ento::MemRegion *
+  topRegionUsedByWait(const clang::ento::CallEvent &CE) const;
+
+  const std::unique_ptr<MPIFunctionClassifier> FuncClassifier;
+  const std::unique_ptr<MPIBugReporter> BReporter;
+  bool IsInitialized{false};
+};
+
+} // end of namespace: mpi
+} // end of namespace: ento
+} // end of namespace: clang
+
+#endif
diff --git a/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPIFunctionClassifier.cpp b/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPIFunctionClassifier.cpp
@@ -0,0 +1,291 @@
+//===-- MPIFunctionClassifier.cpp - classifies MPI functions ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file defines functionality to identify and classify MPI functions.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MPIFunctionClassifier.h"
+#include "llvm/ADT/STLExtras.h"
+
+namespace clang {
+namespace ento {
+namespace mpi {
+
+void MPIFunctionClassifier::identifierInit(AnalysisManager &AM) {
+  // Initialize function identifiers.
+  initPointToPointIdentifiers(AM);
+  initCollectiveIdentifiers(AM);
+  initAdditionalIdentifiers(AM);
+}
+
+void MPIFunctionClassifier::initPointToPointIdentifiers(
+    clang::ento::AnalysisManager &AM) {
+  ASTContext &ASTCtx = AM.getASTContext();
+
+  // Copy identifiers into the correct classification containers.
+  IdentInfo_MPI_Send = &ASTCtx.Idents.get("MPI_Send");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Send);
+  MPIType.push_back(IdentInfo_MPI_Send);
+  assert(IdentInfo_MPI_Send);
+
+  IdentInfo_MPI_Isend = &ASTCtx.Idents.get("MPI_Isend");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Isend);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Isend);
+  MPIType.push_back(IdentInfo_MPI_Isend);
+  assert(IdentInfo_MPI_Isend);
+
+  IdentInfo_MPI_Ssend = &ASTCtx.Idents.get("MPI_Ssend");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Ssend);
+  MPIType.push_back(IdentInfo_MPI_Ssend);
+  assert(IdentInfo_MPI_Ssend);
+
+  IdentInfo_MPI_Issend = &ASTCtx.Idents.get("MPI_Issend");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Issend);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Issend);
+  MPIType.push_back(IdentInfo_MPI_Issend);
+  assert(IdentInfo_MPI_Issend);
+
+  IdentInfo_MPI_Bsend = &ASTCtx.Idents.get("MPI_Bsend");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Bsend);
+  MPIType.push_back(IdentInfo_MPI_Bsend);
+  assert(IdentInfo_MPI_Bsend);
+
+  IdentInfo_MPI_Ibsend = &ASTCtx.Idents.get("MPI_Ibsend");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Ibsend);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Ibsend);
+  MPIType.push_back(IdentInfo_MPI_Ibsend);
+  assert(IdentInfo_MPI_Ibsend);
+
+  IdentInfo_MPI_Rsend = &ASTCtx.Idents.get("MPI_Rsend");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Rsend);
+  MPIType.push_back(IdentInfo_MPI_Rsend);
+  assert(IdentInfo_MPI_Rsend);
+
+  IdentInfo_MPI_Irsend = &ASTCtx.Idents.get("MPI_Irsend");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Irsend);
+  MPIType.push_back(IdentInfo_MPI_Irsend);
+  assert(IdentInfo_MPI_Irsend);
+
+  IdentInfo_MPI_Recv = &ASTCtx.Idents.get("MPI_Recv");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Recv);
+  MPIType.push_back(IdentInfo_MPI_Recv);
+  assert(IdentInfo_MPI_Recv);
+
+  IdentInfo_MPI_Irecv = &ASTCtx.Idents.get("MPI_Irecv");
+  MPIPointToPointTypes.push_back(IdentInfo_MPI_Irecv);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Irecv);
+  MPIType.push_back(IdentInfo_MPI_Irecv);
+  assert(IdentInfo_MPI_Irecv);
+}
+
+void MPIFunctionClassifier::initCollectiveIdentifiers(AnalysisManager &AM) {
+  ASTContext &ASTCtx = AM.getASTContext();
+
+  // Copy identifiers into the correct classification containers.
+  IdentInfo_MPI_Scatter = &ASTCtx.Idents.get("MPI_Scatter");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Scatter);
+  MPIPointToCollTypes.push_back(IdentInfo_MPI_Scatter);
+  MPIType.push_back(IdentInfo_MPI_Scatter);
+  assert(IdentInfo_MPI_Scatter);
+
+  IdentInfo_MPI_Iscatter = &ASTCtx.Idents.get("MPI_Iscatter");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Iscatter);
+  MPIPointToCollTypes.push_back(IdentInfo_MPI_Iscatter);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Iscatter);
+  MPIType.push_back(IdentInfo_MPI_Iscatter);
+  assert(IdentInfo_MPI_Iscatter);
+
+  IdentInfo_MPI_Gather = &ASTCtx.Idents.get("MPI_Gather");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Gather);
+  MPICollToPointTypes.push_back(IdentInfo_MPI_Gather);
+  MPIType.push_back(IdentInfo_MPI_Gather);
+  assert(IdentInfo_MPI_Gather);
+
+  IdentInfo_MPI_Igather = &ASTCtx.Idents.get("MPI_Igather");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Igather);
+  MPICollToPointTypes.push_back(IdentInfo_MPI_Igather);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Igather);
+  MPIType.push_back(IdentInfo_MPI_Igather);
+  assert(IdentInfo_MPI_Igather);
+
+  IdentInfo_MPI_Allgather = &ASTCtx.Idents.get("MPI_Allgather");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Allgather);
+  MPICollToCollTypes.push_back(IdentInfo_MPI_Allgather);
+  MPIType.push_back(IdentInfo_MPI_Allgather);
+  assert(IdentInfo_MPI_Allgather);
+
+  IdentInfo_MPI_Iallgather = &ASTCtx.Idents.get("MPI_Iallgather");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Iallgather);
+  MPICollToCollTypes.push_back(IdentInfo_MPI_Iallgather);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Iallgather);
+  MPIType.push_back(IdentInfo_MPI_Iallgather);
+  assert(IdentInfo_MPI_Iallgather);
+
+  IdentInfo_MPI_Bcast = &ASTCtx.Idents.get("MPI_Bcast");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Bcast);
+  MPIPointToCollTypes.push_back(IdentInfo_MPI_Bcast);
+  MPIType.push_back(IdentInfo_MPI_Bcast);
+  assert(IdentInfo_MPI_Bcast);
+
+  IdentInfo_MPI_Ibcast = &ASTCtx.Idents.get("MPI_Ibcast");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Ibcast);
+  MPIPointToCollTypes.push_back(IdentInfo_MPI_Ibcast);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Ibcast);
+  MPIType.push_back(IdentInfo_MPI_Ibcast);
+  assert(IdentInfo_MPI_Ibcast);
+
+  IdentInfo_MPI_Reduce = &ASTCtx.Idents.get("MPI_Reduce");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Reduce);
+  MPICollToPointTypes.push_back(IdentInfo_MPI_Reduce);
+  MPIType.push_back(IdentInfo_MPI_Reduce);
+  assert(IdentInfo_MPI_Reduce);
+
+  IdentInfo_MPI_Ireduce = &ASTCtx.Idents.get("MPI_Ireduce");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Ireduce);
+  MPICollToPointTypes.push_back(IdentInfo_MPI_Ireduce);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Ireduce);
+  MPIType.push_back(IdentInfo_MPI_Ireduce);
+  assert(IdentInfo_MPI_Ireduce);
+
+  IdentInfo_MPI_Allreduce = &ASTCtx.Idents.get("MPI_Allreduce");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Allreduce);
+  MPICollToCollTypes.push_back(IdentInfo_MPI_Allreduce);
+  MPIType.push_back(IdentInfo_MPI_Allreduce);
+  assert(IdentInfo_MPI_Allreduce);
+
+  IdentInfo_MPI_Iallreduce = &ASTCtx.Idents.get("MPI_Iallreduce");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Iallreduce);
+  MPICollToCollTypes.push_back(IdentInfo_MPI_Iallreduce);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Iallreduce);
+  MPIType.push_back(IdentInfo_MPI_Iallreduce);
+  assert(IdentInfo_MPI_Iallreduce);
+
+  IdentInfo_MPI_Alltoall = &ASTCtx.Idents.get("MPI_Alltoall");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Alltoall);
+  MPICollToCollTypes.push_back(IdentInfo_MPI_Alltoall);
+  MPIType.push_back(IdentInfo_MPI_Alltoall);
+  assert(IdentInfo_MPI_Alltoall);
+
+  IdentInfo_MPI_Ialltoall = &ASTCtx.Idents.get("MPI_Ialltoall");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Ialltoall);
+  MPICollToCollTypes.push_back(IdentInfo_MPI_Ialltoall);
+  MPINonBlockingTypes.push_back(IdentInfo_MPI_Ialltoall);
+  MPIType.push_back(IdentInfo_MPI_Ialltoall);
+  assert(IdentInfo_MPI_Ialltoall);
+}
+
+void MPIFunctionClassifier::initAdditionalIdentifiers(AnalysisManager &AM) {
+  ASTContext &ASTCtx = AM.getASTContext();
+
+  IdentInfo_MPI_Comm_rank = &ASTCtx.Idents.get("MPI_Comm_rank");
+  MPIType.push_back(IdentInfo_MPI_Comm_rank);
+  assert(IdentInfo_MPI_Comm_rank);
+
+  IdentInfo_MPI_Comm_size = &ASTCtx.Idents.get("MPI_Comm_size");
+  MPIType.push_back(IdentInfo_MPI_Comm_size);
+  assert(IdentInfo_MPI_Comm_size);
+
+  IdentInfo_MPI_Wait = &ASTCtx.Idents.get("MPI_Wait");
+  MPIType.push_back(IdentInfo_MPI_Wait);
+  assert(IdentInfo_MPI_Wait);
+
+  IdentInfo_MPI_Waitall = &ASTCtx.Idents.get("MPI_Waitall");
+  MPIType.push_back(IdentInfo_MPI_Waitall);
+  assert(IdentInfo_MPI_Waitall);
+
+  IdentInfo_MPI_Barrier = &ASTCtx.Idents.get("MPI_Barrier");
+  MPICollectiveTypes.push_back(IdentInfo_MPI_Barrier);
+  MPIType.push_back(IdentInfo_MPI_Barrier);
+  assert(IdentInfo_MPI_Barrier);
+}
+
+// general identifiers
+bool MPIFunctionClassifier::isMPIType(const IdentifierInfo *IdentInfo) const {
+  return llvm::is_contained(MPIType, IdentInfo);
+}
+
+bool MPIFunctionClassifier::isNonBlockingType(
+    const IdentifierInfo *IdentInfo) const {
+  return llvm::is_contained(MPINonBlockingTypes, IdentInfo);
+}
+
+// point-to-point identifiers
+bool MPIFunctionClassifier::isPointToPointType(
+    const IdentifierInfo *IdentInfo) const {
+  return llvm::is_contained(MPIPointToPointTypes, IdentInfo);
+}
+
+// collective identifiers
+bool MPIFunctionClassifier::isCollectiveType(
+    const IdentifierInfo *IdentInfo) const {
+  return llvm::is_contained(MPICollectiveTypes, IdentInfo);
+}
+
+bool MPIFunctionClassifier::isCollToColl(
+    const IdentifierInfo *IdentInfo) const {
+  return llvm::is_contained(MPICollToCollTypes, IdentInfo);
+}
+
+bool MPIFunctionClassifier::isScatterType(
+    const IdentifierInfo *IdentInfo) const {
+  return IdentInfo == IdentInfo_MPI_Scatter ||
+         IdentInfo == IdentInfo_MPI_Iscatter;
+}
+
+bool MPIFunctionClassifier::isGatherType(
+    const IdentifierInfo *IdentInfo) const {
+  return IdentInfo == IdentInfo_MPI_Gather ||
+         IdentInfo == IdentInfo_MPI_Igather ||
+         IdentInfo == IdentInfo_MPI_Allgather ||
+         IdentInfo == IdentInfo_MPI_Iallgather;
+}
+
+bool MPIFunctionClassifier::isAllgatherType(
+    const IdentifierInfo *IdentInfo) const {
+  return IdentInfo == IdentInfo_MPI_Allgather ||
+         IdentInfo == IdentInfo_MPI_Iallgather;
+}
+
+bool MPIFunctionClassifier::isAlltoallType(
+    const IdentifierInfo *IdentInfo) const {
+  return IdentInfo == IdentInfo_MPI_Alltoall ||
+         IdentInfo == IdentInfo_MPI_Ialltoall;
+}
+
+bool MPIFunctionClassifier::isBcastType(const IdentifierInfo *IdentInfo) const {
+  return IdentInfo == IdentInfo_MPI_Bcast || IdentInfo == IdentInfo_MPI_Ibcast;
+}
+
+bool MPIFunctionClassifier::isReduceType(
+    const IdentifierInfo *IdentInfo) const {
+  return IdentInfo == IdentInfo_MPI_Reduce ||
+         IdentInfo == IdentInfo_MPI_Ireduce ||
+         IdentInfo == IdentInfo_MPI_Allreduce ||
+         IdentInfo == IdentInfo_MPI_Iallreduce;
+}
+
+// additional identifiers
+bool MPIFunctionClassifier::isMPI_Wait(const IdentifierInfo *IdentInfo) const {
+  return IdentInfo == IdentInfo_MPI_Wait;
+}
+
+bool MPIFunctionClassifier::isMPI_Waitall(
+    const IdentifierInfo *IdentInfo) const {
+  return IdentInfo == IdentInfo_MPI_Waitall;
+}
+
+bool MPIFunctionClassifier::isWaitType(const IdentifierInfo *IdentInfo) const {
+  return IdentInfo == IdentInfo_MPI_Wait || IdentInfo == IdentInfo_MPI_Waitall;
+}
+
+} // end of namespace: mpi
+} // end of namespace: ento
+} // end of namespace: clang
diff --git a/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPIFunctionClassifier.h b/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPIFunctionClassifier.h
@@ -0,0 +1,97 @@
+//===-- MPIFunctionClassifier.h - classifies MPI functions ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file defines functionality to identify and classify MPI functions.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_STATICANALYZER_CHECKERS_MPICHECKER_MPIFUNCTIONCLASSIFIER_H
+#define LLVM_CLANG_LIB_STATICANALYZER_CHECKERS_MPICHECKER_MPIFUNCTIONCLASSIFIER_H
+
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+
+namespace clang {
+namespace ento {
+namespace mpi {
+
+class MPIFunctionClassifier {
+public:
+  MPIFunctionClassifier(AnalysisManager &AM) { identifierInit(AM); }
+
+  // general identifiers
+  bool isMPIType(const IdentifierInfo *const IdentInfo) const;
+  bool isNonBlockingType(const IdentifierInfo *const IdentInfo) const;
+
+  // point-to-point identifiers
+  bool isPointToPointType(const IdentifierInfo *const IdentInfo) const;
+
+  // collective identifiers
+  bool isCollectiveType(const IdentifierInfo *const IdentInfo) const;
+  bool isCollToColl(const IdentifierInfo *const IdentInfo) const;
+  bool isScatterType(const IdentifierInfo *const IdentInfo) const;
+  bool isGatherType(const IdentifierInfo *const IdentInfo) const;
+  bool isAllgatherType(const IdentifierInfo *const IdentInfo) const;
+  bool isAlltoallType(const IdentifierInfo *const IdentInfo) const;
+  bool isReduceType(const IdentifierInfo *const IdentInfo) const;
+  bool isBcastType(const IdentifierInfo *const IdentInfo) const;
+
+  // additional identifiers
+  bool isMPI_Wait(const IdentifierInfo *const IdentInfo) const;
+  bool isMPI_Waitall(const IdentifierInfo *const IdentInfo) const;
+  bool isWaitType(const IdentifierInfo *const IdentInfo) const;
+
+private:
+  // Initializes function identifiers, to recognize them during analysis.
+  void identifierInit(AnalysisManager &AM);
+  void initPointToPointIdentifiers(AnalysisManager &AM);
+  void initCollectiveIdentifiers(AnalysisManager &AM);
+  void initAdditionalIdentifiers(AnalysisManager &AM);
+
+  // The containers are used, to enable classification of MPI-functions during
+  // analysis.
+  llvm::SmallVector<IdentifierInfo *, 12> MPINonBlockingTypes;
+
+  llvm::SmallVector<IdentifierInfo *, 10> MPIPointToPointTypes;
+  llvm::SmallVector<IdentifierInfo *, 16> MPICollectiveTypes;
+
+  llvm::SmallVector<IdentifierInfo *, 4> MPIPointToCollTypes;
+  llvm::SmallVector<IdentifierInfo *, 4> MPICollToPointTypes;
+  llvm::SmallVector<IdentifierInfo *, 6> MPICollToCollTypes;
+
+  llvm::SmallVector<IdentifierInfo *, 32> MPIType;
+
+  // point-to-point functions
+  IdentifierInfo *IdentInfo_MPI_Send{nullptr}, *IdentInfo_MPI_Isend{nullptr},
+      *IdentInfo_MPI_Ssend{nullptr}, *IdentInfo_MPI_Issend{nullptr},
+      *IdentInfo_MPI_Bsend{nullptr}, *IdentInfo_MPI_Ibsend{nullptr},
+      *IdentInfo_MPI_Rsend{nullptr}, *IdentInfo_MPI_Irsend{nullptr},
+      *IdentInfo_MPI_Recv{nullptr}, *IdentInfo_MPI_Irecv{nullptr};
+
+  // collective functions
+  IdentifierInfo *IdentInfo_MPI_Scatter{nullptr},
+      *IdentInfo_MPI_Iscatter{nullptr}, *IdentInfo_MPI_Gather{nullptr},
+      *IdentInfo_MPI_Igather{nullptr}, *IdentInfo_MPI_Allgather{nullptr},
+      *IdentInfo_MPI_Iallgather{nullptr}, *IdentInfo_MPI_Bcast{nullptr},
+      *IdentInfo_MPI_Ibcast{nullptr}, *IdentInfo_MPI_Reduce{nullptr},
+      *IdentInfo_MPI_Ireduce{nullptr}, *IdentInfo_MPI_Allreduce{nullptr},
+      *IdentInfo_MPI_Iallreduce{nullptr}, *IdentInfo_MPI_Alltoall{nullptr},
+      *IdentInfo_MPI_Ialltoall{nullptr}, *IdentInfo_MPI_Barrier{nullptr};
+
+  // additional functions
+  IdentifierInfo *IdentInfo_MPI_Comm_rank{nullptr},
+      *IdentInfo_MPI_Comm_size{nullptr}, *IdentInfo_MPI_Wait{nullptr},
+      *IdentInfo_MPI_Waitall{nullptr};
+};
+
+} // end of namespace: mpi
+} // end of namespace: ento
+} // end of namespace: clang
+
+#endif
diff --git a/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPITypes.h b/clang/lib/StaticAnalyzer/Checkers/MPI-Checker/MPITypes.h
@@ -0,0 +1,66 @@
+//===-- MPITypes.h - Functionality to model MPI concepts --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides definitions to model concepts of MPI. The mpi::Request
+/// class defines a wrapper class, in order to make MPI requests trackable for
+/// path-sensitive analysis.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_STATICANALYZER_CHECKERS_MPICHECKER_MPITYPES_H
+#define LLVM_CLANG_LIB_STATICANALYZER_CHECKERS_MPICHECKER_MPITYPES_H
+
+#include "MPIFunctionClassifier.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
+#include "llvm/ADT/SmallSet.h"
+
+namespace clang {
+namespace ento {
+namespace mpi {
+
+class Request {
+public:
+  enum State : unsigned char { Nonblocking, Wait };
+
+  Request(State S) : CurrentState{S} {}
+
+  void Profile(llvm::FoldingSetNodeID &Id) const {
+    Id.AddInteger(CurrentState);
+  }
+
+  bool operator==(const Request &ToCompare) const {
+    return CurrentState == ToCompare.CurrentState;
+  }
+
+  const State CurrentState;
+};
+
+} // end of namespace: mpi
+} // end of namespace: ento
+} // end of namespace: clang
+
+// The RequestMap stores MPI requests which are identified by their memory
+// region. Requests are used in MPI to complete nonblocking operations with wait
+// operations. A custom map implementation is used, in order to make it
+// available in an arbitrary amount of translation units.
+struct RequestMap {};
+typedef llvm::ImmutableMap<const clang::ento::MemRegion *,
+                           clang::ento::mpi::Request>
+    RequestMapImpl;
+template <>
+struct clang::ento::ProgramStateTrait<RequestMap>
+    : public clang::ento::ProgramStatePartialTrait<RequestMapImpl> {
+  static void *GDMIndex() {
+    static int index = 0;
+    return &index;
+  }
+};
+
+#endif
diff --git a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -632,6 +632,65 @@ void CXXBaseObjectRegion::printPrettyAsExpr(raw_ostream &os) const {
   superRegion->printPrettyAsExpr(os);
 }
 
+std::string MemRegion::getDescriptiveName(bool UseQuotes) const {
+  std::string VariableName;
+  std::string ArrayIndices;
+  const MemRegion *R = this;
+  SmallString<50> buf;
+  llvm::raw_svector_ostream os(buf);
+
+  // Obtain array indices to add them to the variable name.
+  const ElementRegion *ER = nullptr;
+  while ((ER = R->getAs<ElementRegion>())) {
+    // Index is a ConcreteInt.
+    if (auto CI = ER->getIndex().getAs<nonloc::ConcreteInt>()) {
+      llvm::SmallString<2> Idx;
+      CI->getValue().toString(Idx);
+      ArrayIndices = (llvm::Twine("[") + Idx.str() + "]" + ArrayIndices).str();
+    }
+    // If not a ConcreteInt, try to obtain the variable
+    // name by calling 'getDescriptiveName' recursively.
+    else {
+      std::string Idx = ER->getDescriptiveName(false);
+      if (!Idx.empty()) {
+        ArrayIndices = (llvm::Twine("[") + Idx + "]" + ArrayIndices).str();
+      }
+    }
+    R = ER->getSuperRegion();
+  }
+
+  // Get variable name.
+  if (R && R->canPrintPrettyAsExpr()) {
+    R->printPrettyAsExpr(os);
+    if (UseQuotes) {
+      return (llvm::Twine("'") + os.str() + ArrayIndices + "'").str();
+    } else {
+      return (llvm::Twine(os.str()) + ArrayIndices).str();
+    }
+  }
+
+  return VariableName;
+}
+
+SourceRange MemRegion::sourceRange() const {
+  const VarRegion *const VR = dyn_cast<VarRegion>(this->getBaseRegion());
+  const FieldRegion *const FR = dyn_cast<FieldRegion>(this);
+
+  // Check for more specific regions first.
+  // FieldRegion
+  if (FR) {
+    return FR->getDecl()->getSourceRange();
+  }
+  // VarRegion
+  else if (VR) {
+    return VR->getDecl()->getSourceRange();
+  }
+  // Return invalid source range (can be checked by client).
+  else {
+    return SourceRange{};
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // MemRegionManager methods.
 //===----------------------------------------------------------------------===//

diff --git a/clang/test/Analysis/MPIMock.h b/clang/test/Analysis/MPIMock.h
@@ -0,0 +1,55 @@
+// Message Passing Interface mock header. Mocks MPI constants and functions, in
+// order to make them available in distinct integration test files.
+
+#define NULL 0
+
+// mock types
+typedef int MPI_Datatype;
+typedef int MPI_Comm;
+typedef int MPI_Request;
+typedef int MPI_Status;
+typedef int MPI_Op;
+typedef int int8_t;
+typedef int uint8_t;
+typedef int uint16_t;
+typedef int int64_t;
+namespace std { template<class T> struct complex { T real; T imag; }; }
+
+// mock constants
+#define MPI_DATATYPE_NULL 0
+#define MPI_CHAR 0
+#define MPI_BYTE 0
+#define MPI_INT 0
+#define MPI_LONG 0
+#define MPI_LONG_DOUBLE 0
+#define MPI_UNSIGNED 0
+#define MPI_INT8_T 0
+#define MPI_UINT8_T 0
+#define MPI_UINT16_T 0
+#define MPI_C_LONG_DOUBLE_COMPLEX 0
+#define MPI_FLOAT 0
+#define MPI_DOUBLE 0
+#define MPI_CXX_BOOL 0
+#define MPI_CXX_FLOAT_COMPLEX 0
+#define MPI_CXX_DOUBLE_COMPLEX 0
+#define MPI_CXX_LONG_DOUBLE_COMPLEX 0
+#define MPI_IN_PLACE 0
+#define MPI_COMM_WORLD 0
+#define MPI_STATUS_IGNORE 0
+#define MPI_STATUSES_IGNORE 0
+#define MPI_SUM 0
+
+// mock functions
+int MPI_Comm_size(MPI_Comm, int *);
+int MPI_Comm_rank(MPI_Comm, int *);
+int MPI_Send(const void *, int, MPI_Datatype, int, int, MPI_Comm);
+int MPI_Recv(void *, int, MPI_Datatype, int, int, MPI_Comm, MPI_Status *);
+int MPI_Isend(const void *, int, MPI_Datatype, int, int, MPI_Comm,
+    MPI_Request *);
+int MPI_Irecv(void *, int, MPI_Datatype, int, int, MPI_Comm, MPI_Request *);
+int MPI_Wait(MPI_Request *, MPI_Status *);
+int MPI_Waitall(int, MPI_Request[], MPI_Status[]);
+int MPI_Reduce(const void *, void *, int, MPI_Datatype, MPI_Op, int, MPI_Comm);
+int MPI_Ireduce(const void *, void *, int, MPI_Datatype, MPI_Op, int, MPI_Comm,
+    MPI_Request *);
+int MPI_Bcast(void *, int count, MPI_Datatype, int, MPI_Comm);
diff --git a/clang/test/Analysis/MemRegion.cpp b/clang/test/Analysis/MemRegion.cpp
@@ -0,0 +1,47 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=optin.mpi.MPI-Checker -verify %s
+
+#include "MPIMock.h"
+
+// Use MPI-Checker to test 'getDescriptiveName', as the checker uses the
+// function for diagnostics.
+void testGetDescriptiveName() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Request sendReq1;
+  MPI_Wait(&sendReq1, MPI_STATUS_IGNORE); // expected-warning{{Request 'sendReq1' has no matching nonblocking call.}}
+}
+
+void testGetDescriptiveName2() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Request sendReq1[10][10][10];
+  MPI_Wait(&sendReq1[1][7][9], MPI_STATUS_IGNORE); // expected-warning{{Request 'sendReq1[1][7][9]' has no matching nonblocking call.}}
+}
+
+void testGetDescriptiveName3() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  typedef struct { MPI_Request req; } ReqStruct;
+  ReqStruct rs;
+  MPI_Request *r = &rs.req;
+  MPI_Wait(r, MPI_STATUS_IGNORE); // expected-warning{{Request 'rs.req' has no matching nonblocking call.}}
+}
+
+void testGetDescriptiveName4() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  typedef struct { MPI_Request req[2][2]; } ReqStruct;
+  ReqStruct rs;
+  MPI_Request *r = &rs.req[0][1];
+  MPI_Wait(r, MPI_STATUS_IGNORE); // expected-warning{{Request 'rs.req[0][1]' has no matching nonblocking call.}}
+}
+
+void testGetDescriptiveName5() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  typedef struct { MPI_Request req; } ReqStructInner;
+  typedef struct  { ReqStructInner req; } ReqStruct;
+  ReqStruct rs;
+  MPI_Request *r = &rs.req.req;
+  MPI_Wait(r, MPI_STATUS_IGNORE); // expected-warning{{Request 'rs.req.req' has no matching nonblocking call.}}
+}
diff --git a/clang/test/Analysis/mpichecker.cpp b/clang/test/Analysis/mpichecker.cpp
@@ -0,0 +1,342 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=optin.mpi.MPI-Checker -verify %s
+
+#include "MPIMock.h"
+
+void matchedWait1() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  if (rank >= 0) {
+    MPI_Request sendReq1, recvReq1;
+    MPI_Isend(&buf, 1, MPI_DOUBLE, rank + 1, 0, MPI_COMM_WORLD, &sendReq1);
+    MPI_Irecv(&buf, 1, MPI_DOUBLE, rank - 1, 0, MPI_COMM_WORLD, &recvReq1);
+
+    MPI_Wait(&sendReq1, MPI_STATUS_IGNORE);
+    MPI_Wait(&recvReq1, MPI_STATUS_IGNORE);
+  }
+} // no error
+
+void matchedWait2() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  if (rank >= 0) {
+    MPI_Request sendReq1, recvReq1;
+    MPI_Isend(&buf, 1, MPI_DOUBLE, rank + 1, 0, MPI_COMM_WORLD, &sendReq1);
+    MPI_Irecv(&buf, 1, MPI_DOUBLE, rank - 1, 0, MPI_COMM_WORLD, &recvReq1);
+    MPI_Wait(&sendReq1, MPI_STATUS_IGNORE);
+    MPI_Wait(&recvReq1, MPI_STATUS_IGNORE);
+  }
+} // no error
+
+void matchedWait3() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  if (rank >= 0) {
+    MPI_Request sendReq1, recvReq1;
+    MPI_Isend(&buf, 1, MPI_DOUBLE, rank + 1, 0, MPI_COMM_WORLD, &sendReq1);
+    MPI_Irecv(&buf, 1, MPI_DOUBLE, rank - 1, 0, MPI_COMM_WORLD, &recvReq1);
+
+    if (rank > 1000) {
+      MPI_Wait(&sendReq1, MPI_STATUS_IGNORE);
+      MPI_Wait(&recvReq1, MPI_STATUS_IGNORE);
+    } else {
+      MPI_Wait(&sendReq1, MPI_STATUS_IGNORE);
+      MPI_Wait(&recvReq1, MPI_STATUS_IGNORE);
+    }
+  }
+} // no error
+
+void missingWait1() { // Check missing wait for dead region.
+  double buf = 0;
+  MPI_Request sendReq1;
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD, &sendReq1);
+} // expected-warning{{Request 'sendReq1' has no matching wait.}}
+
+void missingWait2() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  if (rank == 0) {
+  } else {
+    MPI_Request sendReq1, recvReq1;
+
+    MPI_Isend(&buf, 1, MPI_DOUBLE, rank + 1, 0, MPI_COMM_WORLD, &sendReq1);
+    MPI_Irecv(&buf, 1, MPI_DOUBLE, rank - 1, 0, MPI_COMM_WORLD, &recvReq1); // expected-warning{{Request 'sendReq1' has no matching wait.}}
+    MPI_Wait(&recvReq1, MPI_STATUS_IGNORE);
+  }
+}
+
+void doubleNonblocking() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  if (rank == 1) {
+  } else {
+    MPI_Request sendReq1;
+
+    MPI_Isend(&buf, 1, MPI_DOUBLE, rank + 1, 0, MPI_COMM_WORLD, &sendReq1);
+    MPI_Irecv(&buf, 1, MPI_DOUBLE, rank - 1, 0, MPI_COMM_WORLD, &sendReq1); // expected-warning{{Double nonblocking on request 'sendReq1'.}}
+    MPI_Wait(&sendReq1, MPI_STATUS_IGNORE);
+  }
+}
+
+void doubleNonblocking2() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  MPI_Request req;
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD, &req);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD, &req); // expected-warning{{Double nonblocking on request 'req'.}}
+  MPI_Wait(&req, MPI_STATUS_IGNORE);
+}
+
+void doubleNonblocking3() {
+  typedef struct { MPI_Request req; } ReqStruct;
+
+  ReqStruct rs;
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD, &rs.req);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD, &rs.req); // expected-warning{{Double nonblocking on request 'rs.req'.}}
+  MPI_Wait(&rs.req, MPI_STATUS_IGNORE);
+}
+
+void doubleNonblocking4() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  MPI_Request req;
+  for (int i = 0; i < 2; ++i) {
+    MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD, &req); // expected-warning{{Double nonblocking on request 'req'.}}
+  }
+  MPI_Wait(&req, MPI_STATUS_IGNORE);
+}
+
+void tripleNonblocking() {
+  double buf = 0;
+  MPI_Request sendReq;
+  MPI_Isend(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); 
+  MPI_Irecv(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); // expected-warning{{Double nonblocking on request 'sendReq'.}}
+  MPI_Isend(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); // expected-warning{{Double nonblocking on request 'sendReq'.}}
+  MPI_Wait(&sendReq, MPI_STATUS_IGNORE);
+}
+
+void missingNonBlocking() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Request sendReq1[10][10][10];
+  MPI_Wait(&sendReq1[1][7][9], MPI_STATUS_IGNORE); // expected-warning{{Request 'sendReq1[1][7][9]' has no matching nonblocking call.}}
+}
+
+void missingNonBlocking2() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  typedef struct { MPI_Request req[2][2]; } ReqStruct;
+  ReqStruct rs;
+  MPI_Request *r = &rs.req[0][1];
+  MPI_Wait(r, MPI_STATUS_IGNORE); // expected-warning{{Request 'rs.req[0][1]' has no matching nonblocking call.}}
+}
+
+void missingNonBlocking3() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Request sendReq;
+  MPI_Wait(&sendReq, MPI_STATUS_IGNORE); // expected-warning{{Request 'sendReq' has no matching nonblocking call.}}
+}
+
+void missingNonBlockingMultiple() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Request sendReq[4];
+  for (int i = 0; i < 4; ++i) {
+    MPI_Wait(&sendReq[i], MPI_STATUS_IGNORE); // expected-warning-re 1+{{Request {{.*}} has no matching nonblocking call.}}
+  }
+}
+
+void missingNonBlockingWaitall() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Request req[4];
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+      &req[0]);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+      &req[1]);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+      &req[3]);
+
+  MPI_Waitall(4, req, MPI_STATUSES_IGNORE); // expected-warning{{Request 'req[2]' has no matching nonblocking call.}}
+}
+
+void missingNonBlockingWaitall2() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Request req[4];
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+      &req[0]);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+      &req[3]);
+
+  MPI_Waitall(4, req, MPI_STATUSES_IGNORE); // expected-warning-re 2{{Request '{{(.*)[[1-2]](.*)}}' has no matching nonblocking call.}}
+}
+
+void missingNonBlockingWaitall3() {
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Request req[4];
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+      &req[0]);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+      &req[2]);
+
+  MPI_Waitall(4, req, MPI_STATUSES_IGNORE); // expected-warning-re 2{{Request '{{(.*)[[1,3]](.*)}}' has no matching nonblocking call.}}
+}
+
+void missingNonBlockingWaitall4() {
+  int rank = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+  MPI_Request req[4];
+  MPI_Waitall(4, req, MPI_STATUSES_IGNORE); // expected-warning-re 4{{Request '{{(.*)[[0-3]](.*)}}' has no matching nonblocking call.}}
+}
+
+void noDoubleRequestUsage() {
+  typedef struct {
+    MPI_Request req;
+    MPI_Request req2;
+  } ReqStruct;
+
+  ReqStruct rs;
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &rs.req);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &rs.req2);
+  MPI_Wait(&rs.req, MPI_STATUS_IGNORE);
+  MPI_Wait(&rs.req2, MPI_STATUS_IGNORE);
+} // no error
+
+void noDoubleRequestUsage2() {
+  typedef struct {
+    MPI_Request req[2];
+    MPI_Request req2;
+  } ReqStruct;
+
+  ReqStruct rs;
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &rs.req[0]);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &rs.req[1]);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &rs.req2);
+  MPI_Wait(&rs.req[0], MPI_STATUS_IGNORE);
+  MPI_Wait(&rs.req[1], MPI_STATUS_IGNORE);
+  MPI_Wait(&rs.req2, MPI_STATUS_IGNORE);
+} // no error
+
+void nestedRequest() {
+  typedef struct {
+    MPI_Request req[2];
+    MPI_Request req2;
+  } ReqStruct;
+
+  ReqStruct rs;
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &rs.req[0]);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &rs.req[1]);
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &rs.req2);
+  MPI_Waitall(2, rs.req, MPI_STATUSES_IGNORE);
+  MPI_Wait(&rs.req2, MPI_STATUS_IGNORE);
+} // no error
+
+void singleRequestInWaitall() {
+  MPI_Request r;
+  int rank = 0;
+  double buf = 0;
+  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &r);
+  MPI_Waitall(1, &r, MPI_STATUSES_IGNORE);
+} // no error
+
+void multiRequestUsage() {
+  double buf = 0;
+  MPI_Request req;
+
+  MPI_Isend(&buf, 1, MPI_DOUBLE, 1, 0, MPI_COMM_WORLD, &req);
+  MPI_Wait(&req, MPI_STATUS_IGNORE);
+
+  MPI_Irecv(&buf, 1, MPI_DOUBLE, 1, 0, MPI_COMM_WORLD, &req);
+  MPI_Wait(&req, MPI_STATUS_IGNORE);
+} // no error
+
+void multiRequestUsage2() {
+  double buf = 0;
+  MPI_Request req;
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &req);
+  MPI_Wait(&req, MPI_STATUS_IGNORE);
+
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &req);
+  MPI_Wait(&req, MPI_STATUS_IGNORE);
+} // no error
+
+// wrapper function 
+void callNonblocking(MPI_Request *req) {
+  double buf = 0;
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+             req);
+}
+
+// wrapper function
+void callWait(MPI_Request *req) {
+  MPI_Wait(req, MPI_STATUS_IGNORE);
+} 
+
+// Call nonblocking, wait wrapper functions.
+void callWrapperFunctions() {
+  MPI_Request req;
+  callNonblocking(&req);
+  callWait(&req);
+} // no error
+
+void externFunctions1() {
+  double buf = 0;
+  MPI_Request req;
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD,
+              &req);
+  void callWaitExtern(MPI_Request *req); 
+  callWaitExtern(&req); 
+} // expected-warning{{Request 'req' has no matching wait.}}
+
+void externFunctions2() {
+  MPI_Request req;
+  void callNonblockingExtern(MPI_Request *req); 
+  callNonblockingExtern(&req); 
+}
diff --git a/clang/test/Analysis/mpicheckernotes.cpp b/clang/test/Analysis/mpicheckernotes.cpp
@@ -0,0 +1,34 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=optin.mpi.MPI-Checker -analyzer-output=text -verify %s
+
+// MPI-Checker test file to test note diagnostics.
+
+#include "MPIMock.h"
+
+void doubleNonblocking() {
+  double buf = 0;
+  MPI_Request sendReq;
+  MPI_Isend(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); // expected-note{{Request is previously used by nonblocking call here.}}
+  MPI_Irecv(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); // expected-warning{{Double nonblocking on request 'sendReq'.}} expected-note{{Double nonblocking on request 'sendReq'.}}
+  MPI_Wait(&sendReq, MPI_STATUS_IGNORE);
+}
+
+void missingWait() {
+  double buf = 0;
+  MPI_Request sendReq;
+  MPI_Ireduce(MPI_IN_PLACE, &buf, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD, &sendReq); // expected-note{{Request is previously used by nonblocking call here.}}
+} // expected-warning{{Request 'sendReq' has no matching wait.}} expected-note{{Request 'sendReq' has no matching wait.}}
+
+// If more than 2 nonblocking calls are using a request in a sequence, they all
+// point to the first call as the 'previous' call. This is because the
+// BugReporterVisitor only checks for differences in state or existence of an
+// entity.
+void tripleNonblocking() {
+  double buf = 0;
+  MPI_Request sendReq;
+  MPI_Isend(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); // expected-note 2{{Request is previously used by nonblocking call here.}}
+  MPI_Irecv(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); // expected-warning{{Double nonblocking on request 'sendReq'.}} expected-note{{Double nonblocking on request 'sendReq'.}}
+
+  MPI_Isend(&buf, 1, MPI_DOUBLE, 0, 0, MPI_COMM_WORLD, &sendReq); // expected-warning{{Double nonblocking on request 'sendReq'.}} expected-note{{Double nonblocking on request 'sendReq'.}}
+
+  MPI_Wait(&sendReq, MPI_STATUS_IGNORE);
+}