diff --git a/clang/lib/StaticAnalyzer/Checkers/SmartPtr.h b/clang/lib/StaticAnalyzer/Checkers/SmartPtr.h
--- a/clang/lib/StaticAnalyzer/Checkers/SmartPtr.h
+++ b/clang/lib/StaticAnalyzer/Checkers/SmartPtr.h
@@ -22,6 +22,8 @@
 
 /// Returns true if the event call is on smart pointer.
 bool isStdSmartPtrCall(const CallEvent &Call);
+bool isStdSmartPtr(const CXXRecordDecl *RD);
+bool isStdSmartPtr(const Expr *E);
 
 /// Returns whether the smart pointer is null or not.
 bool isNullSmartPtr(const ProgramStateRef State, const MemRegion *ThisRegion);
diff --git a/clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp b/clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp
--- a/clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp
@@ -68,6 +68,7 @@
   bool updateMovedSmartPointers(CheckerContext &C, const MemRegion *ThisRegion,
                                 const MemRegion *OtherSmartPtrRegion) const;
   void handleBoolConversion(const CallEvent &Call, CheckerContext &C) const;
+  bool handleComparisionOp(const CallEvent &Call, CheckerContext &C) const;
 
   using SmartPtrMethodHandlerFn =
       void (SmartPtrModeling::*)(const CallEvent &Call, CheckerContext &) const;
@@ -89,18 +90,24 @@
   const auto *MethodDecl = dyn_cast_or_null<CXXMethodDecl>(Call.getDecl());
   if (!MethodDecl || !MethodDecl->getParent())
     return false;
+  return isStdSmartPtr(MethodDecl->getParent());
+}
 
-  const auto *RecordDecl = MethodDecl->getParent();
-  if (!RecordDecl || !RecordDecl->getDeclContext()->isStdNamespace())
+bool isStdSmartPtr(const CXXRecordDecl *RD) {
+  if (!RD || !RD->getDeclContext()->isStdNamespace())
     return false;
 
-  if (RecordDecl->getDeclName().isIdentifier()) {
-    StringRef Name = RecordDecl->getName();
+  if (RD->getDeclName().isIdentifier()) {
+    StringRef Name = RD->getName();
     return Name == "shared_ptr" || Name == "unique_ptr" || Name == "weak_ptr";
   }
   return false;
 }
 
+bool isStdSmartPtr(const Expr *E) {
+  return isStdSmartPtr(E->getType()->getAsCXXRecordDecl());
+}
+
 bool isNullSmartPtr(const ProgramStateRef State, const MemRegion *ThisRegion) {
   const auto *InnerPointVal = State->get<TrackedRegionMap>(ThisRegion);
   return InnerPointVal &&
@@ -135,18 +142,11 @@
   return State;
 }
 
-// Helper method to get the inner pointer type of specialized smart pointer
-// Returns empty type if not found valid inner pointer type.
-static QualType getInnerPointerType(const CallEvent &Call, CheckerContext &C) {
-  const auto *MethodDecl = dyn_cast_or_null<CXXMethodDecl>(Call.getDecl());
-  if (!MethodDecl || !MethodDecl->getParent())
+static QualType getInnerPointerType(CheckerContext C, const CXXRecordDecl *RD) {
+  if (!RD || !RD->isInStdNamespace())
     return {};
 
-  const auto *RecordDecl = MethodDecl->getParent();
-  if (!RecordDecl || !RecordDecl->isInStdNamespace())
-    return {};
-
-  const auto *TSD = dyn_cast<ClassTemplateSpecializationDecl>(RecordDecl);
+  const auto *TSD = dyn_cast<ClassTemplateSpecializationDecl>(RD);
   if (!TSD)
     return {};
 
@@ -157,6 +157,17 @@
   return C.getASTContext().getPointerType(InnerValueType.getCanonicalType());
 }
 
+// Helper method to get the inner pointer type of specialized smart pointer
+// Returns empty type if not found valid inner pointer type.
+static QualType getInnerPointerType(const CallEvent &Call, CheckerContext &C) {
+  const auto *MethodDecl = dyn_cast_or_null<CXXMethodDecl>(Call.getDecl());
+  if (!MethodDecl || !MethodDecl->getParent())
+    return {};
+
+  const auto *RecordDecl = MethodDecl->getParent();
+  return getInnerPointerType(C, RecordDecl);
+}
+
 // Helper method to pretty print region and avoid extra spacing.
 static void checkAndPrettyPrintRegion(llvm::raw_ostream &OS,
                                       const MemRegion *Region) {
@@ -178,6 +189,16 @@
 bool SmartPtrModeling::evalCall(const CallEvent &Call,
                                 CheckerContext &C) const {
   ProgramStateRef State = C.getState();
+
+  // If any one of the arg is a unique_ptr, then
+  // we can try this function
+  if (Call.getNumArgs() == 2 &&
+      Call.getDecl()->getDeclContext()->isStdNamespace())
+    if (smartptr::isStdSmartPtr(Call.getArgExpr(0)) ||
+        smartptr::isStdSmartPtr(Call.getArgExpr(1)))
+      if (handleComparisionOp(Call, C))
+        return true;
+
   if (!smartptr::isStdSmartPtrCall(Call))
     return false;
 
@@ -272,6 +293,86 @@
   return C.isDifferent();
 }
 
+bool SmartPtrModeling::handleComparisionOp(const CallEvent &Call,
+                                           CheckerContext &C) const {
+  const auto *FC = dyn_cast<SimpleFunctionCall>(&Call);
+  if (!FC)
+    return false;
+  const FunctionDecl *FD = FC->getDecl();
+  if (!FD->isOverloadedOperator())
+    return false;
+  const OverloadedOperatorKind OOK = FD->getOverloadedOperator();
+  if (!(OOK == OO_EqualEqual || OOK == OO_ExclaimEqual || OOK == OO_Less ||
+        OOK == OO_LessEqual || OOK == OO_Greater || OOK == OO_GreaterEqual ||
+        OOK == OO_Spaceship))
+    return false;
+
+  // There are some special cases about which we can infer about
+  // the resulting answer.
+  // For reference, there is a discussion at https://reviews.llvm.org/D104616.
+  // Also, the cppreference page is good to look at
+  // https://en.cppreference.com/w/cpp/memory/unique_ptr/operator_cmp.
+
+  ProgramStateRef State = C.getState();
+
+  auto retrieveOrConjureInnerPtrVal = [&C, &State](const Expr *E,
+                                                   SVal S) -> SVal {
+    if (S.isZeroConstant()) {
+      return C.getSValBuilder().makeZeroVal(E->getType());
+    }
+    const MemRegion *Reg = S.getAsRegion();
+    assert(Reg &&
+           "this pointer of std::unique_ptr should be obtainable as MemRegion");
+    const auto *Ptr = State->get<TrackedRegionMap>(Reg);
+    if (Ptr)
+      return *Ptr;
+    return C.getSValBuilder().conjureSymbolVal(
+        E, C.getLocationContext(),
+        getInnerPointerType(C, E->getType()->getAsCXXRecordDecl()),
+        C.blockCount());
+  };
+
+  BinaryOperatorKind BOK;
+  switch (OOK) {
+  case OO_EqualEqual:
+    BOK = BO_EQ;
+    break;
+  case OO_ExclaimEqual:
+    BOK = BO_NE;
+    break;
+  case OO_GreaterEqual:
+    BOK = BO_GE;
+    break;
+  case OO_LessEqual:
+    BOK = BO_LE;
+    break;
+  case OO_Less:
+    BOK = BO_LT;
+    break;
+  case OO_Greater:
+    BOK = BO_GT;
+    break;
+  case OO_Spaceship:
+    BOK = BO_Cmp;
+    break;
+  default:
+    llvm_unreachable("unexpected overloaded operator kind");
+  }
+
+  SVal First = Call.getArgSVal(0);
+  SVal Second = Call.getArgSVal(1);
+  const auto *FirstExpr = Call.getArgExpr(0);
+  const auto *SecondExpr = Call.getArgExpr(1);
+
+  SVal FirstPtrVal = retrieveOrConjureInnerPtrVal(FirstExpr, First);
+  SVal SecondPtrVal = retrieveOrConjureInnerPtrVal(SecondExpr, Second);
+  auto RetVal = C.getSValBuilder().evalBinOp(
+      State, BOK, FirstPtrVal, SecondPtrVal, Call.getResultType());
+  State = State->BindExpr(Call.getOriginExpr(), C.getLocationContext(), RetVal);
+  C.addTransition(State);
+  return true;
+}
+
 void SmartPtrModeling::checkDeadSymbols(SymbolReaper &SymReaper,
                                         CheckerContext &C) const {
   ProgramStateRef State = C.getState();
diff --git a/clang/test/Analysis/Inputs/system-header-simulator-cxx.h b/clang/test/Analysis/Inputs/system-header-simulator-cxx.h
--- a/clang/test/Analysis/Inputs/system-header-simulator-cxx.h
+++ b/clang/test/Analysis/Inputs/system-header-simulator-cxx.h
@@ -978,6 +978,61 @@
 void swap(unique_ptr<T> &x, unique_ptr<T> &y) noexcept {
   x.swap(y);
 }
+
+template <typename T1, typename T2>
+bool operator==(const unique_ptr<T1> &x, const unique_ptr<T2> &y);
+
+template <typename T1, typename T2>
+bool operator!=(const unique_ptr<T1> &x, const unique_ptr<T2> &y);
+
+template <typename T1, typename T2>
+bool operator<(const unique_ptr<T1> &x, const unique_ptr<T2> &y);
+
+template <typename T1, typename T2>
+bool operator>(const unique_ptr<T1> &x, const unique_ptr<T2> &y);
+
+template <typename T1, typename T2>
+bool operator<=(const unique_ptr<T1> &x, const unique_ptr<T2> &y);
+
+template <typename T1, typename T2>
+bool operator>=(const unique_ptr<T1> &x, const unique_ptr<T2> &y);
+
+template <typename T>
+bool operator==(const unique_ptr<T> &x, nullptr_t y);
+
+template <typename T>
+bool operator!=(const unique_ptr<T> &x, nullptr_t y);
+
+template <typename T>
+bool operator<(const unique_ptr<T> &x, nullptr_t y);
+
+template <typename T>
+bool operator>(const unique_ptr<T> &x, nullptr_t y);
+
+template <typename T>
+bool operator<=(const unique_ptr<T> &x, nullptr_t y);
+
+template <typename T>
+bool operator>=(const unique_ptr<T> &x, nullptr_t y);
+
+template <typename T>
+bool operator==(nullptr_t x, const unique_ptr<T> &y);
+
+template <typename T>
+bool operator!=(nullptr_t x, const unique_ptr<T> &y);
+
+template <typename T>
+bool operator>(nullptr_t x, const unique_ptr<T> &y);
+
+template <typename T>
+bool operator<(nullptr_t x, const unique_ptr<T> &y);
+
+template <typename T>
+bool operator>=(nullptr_t x, const unique_ptr<T> &y);
+
+template <typename T>
+bool operator<=(nullptr_t x, const unique_ptr<T> &y);
+
 } // namespace std
 #endif
 
diff --git a/clang/test/Analysis/smart-ptr.cpp b/clang/test/Analysis/smart-ptr.cpp
--- a/clang/test/Analysis/smart-ptr.cpp
+++ b/clang/test/Analysis/smart-ptr.cpp
@@ -457,3 +457,32 @@
     P->foo(); // expected-warning {{Dereference of null smart pointer 'P' [alpha.cplusplus.SmartPtr]}}
   }
 }
+
+// The following is a silly function,
+// but serves to test if we are picking out
+// standard comparision functions from custom ones.
+template <typename T>
+bool operator<(std::unique_ptr<T> &x, double d);
+
+void uniquePtrComparision(std::unique_ptr<int> unknownPtr) {
+  auto ptr = std::unique_ptr<int>(new int(13));
+  auto nullPtr = std::unique_ptr<int>();
+  auto otherPtr = std::unique_ptr<int>(new int(29));
+
+  clang_analyzer_eval(ptr == ptr); // expected-warning{{TRUE}}
+  clang_analyzer_eval(ptr > ptr);  // expected-warning{{FALSE}}
+  clang_analyzer_eval(ptr <= ptr); // expected-warning{{TRUE}}
+
+  clang_analyzer_eval(nullPtr <= unknownPtr); // expected-warning{{TRUE}}
+  clang_analyzer_eval(unknownPtr >= nullPtr); // expected-warning{{TRUE}}
+
+  clang_analyzer_eval(ptr != otherPtr); // expected-warning{{TRUE}}
+  clang_analyzer_eval(ptr > nullPtr);   // expected-warning{{TRUE}}
+
+  clang_analyzer_eval(ptr != nullptr);        // expected-warning{{TRUE}}
+  clang_analyzer_eval(nullPtr != nullptr);    // expected-warning{{FALSE}}
+  clang_analyzer_eval(nullptr <= unknownPtr); // expected-warning{{TRUE}}
+  clang_analyzer_eval(nullptr < unknownPtr);  // expected-warning{{UNKNOWN}}
+
+  clang_analyzer_eval(ptr < 2.0); // expected-warning{{UNKNOWN}}
+}