diff --git a/clang/include/clang/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.h b/clang/include/clang/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.h
--- a/clang/include/clang/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.h
+++ b/clang/include/clang/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.h
@@ -59,6 +59,10 @@
   void transfer(const Stmt *Stmt, SourceLocationsLattice &State,
                 Environment &Env);
 
+  bool merge(QualType Type, const Value &Val1, const Environment &Env1,
+             const Value &Val2, const Environment &Env2, Value &MergedVal,
+             Environment &MergedEnv) override;
+
 private:
   MatchSwitch<TransferState<SourceLocationsLattice>> TransferMatchSwitch;
 };
diff --git a/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp b/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
--- a/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.cpp
@@ -158,18 +158,24 @@
                                ComparesToSame(integerLiteral(equals(0)))));
 }
 
+/// Sets `HasValueVal` as the symbolic value that represents the "has_value"
+/// property of the optional value `OptionalVal`.
+void setHasValue(StructValue &OptionalVal, BoolValue &HasValueVal) {
+  OptionalVal.setProperty("has_value", HasValueVal);
+}
+
 /// Creates a symbolic value for an `optional` value using `HasValueVal` as the
 /// symbolic value of its "has_value" property.
 StructValue &createOptionalValue(Environment &Env, BoolValue &HasValueVal) {
   auto OptionalVal = std::make_unique<StructValue>();
-  OptionalVal->setProperty("has_value", HasValueVal);
+  setHasValue(*OptionalVal, HasValueVal);
   return Env.takeOwnership(std::move(OptionalVal));
 }
 
 /// Returns the symbolic value that represents the "has_value" property of the
 /// optional value `Val`. Returns null if `Val` is null.
-BoolValue *getHasValue(Value *Val) {
-  if (auto *OptionalVal = cast_or_null<StructValue>(Val)) {
+BoolValue *getHasValue(const Value *Val) {
+  if (const auto *OptionalVal = cast_or_null<StructValue>(Val)) {
     return cast<BoolValue>(OptionalVal->getProperty("has_value"));
   }
   return nullptr;
@@ -213,7 +219,7 @@
   if (auto *OptionalVal = cast_or_null<StructValue>(
           State.Env.getValue(*OptionalExpr, SkipPast::Reference))) {
     if (OptionalVal->getProperty("has_value") == nullptr) {
-      OptionalVal->setProperty("has_value", State.Env.makeAtomicBoolValue());
+      setHasValue(*OptionalVal, State.Env.makeAtomicBoolValue());
     }
   }
 }
@@ -570,5 +576,28 @@
   TransferMatchSwitch(*S, getASTContext(), State);
 }
 
+bool UncheckedOptionalAccessModel::merge(QualType Type, const Value &Val1,
+                                         const Environment &Env1,
+                                         const Value &Val2,
+                                         const Environment &Env2,
+                                         Value &MergedVal,
+                                         Environment &MergedEnv) {
+  if (!IsOptionalType(Type))
+    return true;
+
+  auto *HasValueVal1 = getHasValue(&Val1);
+  assert(HasValueVal1 != nullptr);
+
+  auto *HasValueVal2 = getHasValue(&Val2);
+  assert(HasValueVal2 != nullptr);
+
+  setHasValue(
+      *cast<StructValue>(&MergedVal),
+      MergedEnv.makeOr(
+          MergedEnv.makeAnd(Env1.getFlowConditionToken(), *HasValueVal1),
+          MergedEnv.makeAnd(Env2.getFlowConditionToken(), *HasValueVal2)));
+  return true;
+}
+
 } // namespace dataflow
 } // namespace clang
diff --git a/clang/unittests/Analysis/FlowSensitive/UncheckedOptionalAccessModelTest.cpp b/clang/unittests/Analysis/FlowSensitive/UncheckedOptionalAccessModelTest.cpp
--- a/clang/unittests/Analysis/FlowSensitive/UncheckedOptionalAccessModelTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/UncheckedOptionalAccessModelTest.cpp
@@ -1852,7 +1852,25 @@
   )",
                          UnorderedElementsAre(Pair("check", "safe")));
 
-  // FIXME: Add tests that call `emplace` in conditional branches.
+  ExpectLatticeChecksFor(
+      R"(
+    #include "unchecked_optional_access_test.h"
+
+    void target($ns::$optional<int> opt, bool b) {
+      if (b) {
+        opt.emplace(0);
+      }
+      if (b) {
+        opt.value();
+        /*[[check-1]]*/
+      } else {
+        opt.value();
+        /*[[check-2]]*/
+      }
+    }
+  )",
+      UnorderedElementsAre(Pair("check-1", "safe"),
+                           Pair("check-2", "unsafe: input.cc:12:9")));
 }
 
 TEST_P(UncheckedOptionalAccessTest, Reset) {
@@ -1883,7 +1901,26 @@
   )",
       UnorderedElementsAre(Pair("check", "unsafe: input.cc:7:9")));
 
-  // FIXME: Add tests that call `reset` in conditional branches.
+  ExpectLatticeChecksFor(
+      R"(
+    #include "unchecked_optional_access_test.h"
+
+    void target(bool b) {
+      $ns::$optional<int> opt = $ns::make_optional(0);
+      if (b) {
+        opt.reset();
+      }
+      if (b) {
+        opt.value();
+        /*[[check-1]]*/
+      } else {
+        opt.value();
+        /*[[check-2]]*/
+      }
+    }
+  )",
+      UnorderedElementsAre(Pair("check-1", "unsafe: input.cc:10:9"),
+                           Pair("check-2", "safe")));
 }
 
 TEST_P(UncheckedOptionalAccessTest, ValueAssignment) {
@@ -2150,6 +2187,106 @@
       UnorderedElementsAre(Pair("check-1", "safe"), Pair("check-2", "safe")));
 }
 
+TEST_P(UncheckedOptionalAccessTest, CorrelatedBranches) {
+  ExpectLatticeChecksFor(R"code(
+    #include "unchecked_optional_access_test.h"
+
+    void target(bool b, $ns::$optional<int> opt) {
+      if (b || opt.has_value()) {
+        if (!b) {
+          opt.value();
+          /*[[check]]*/
+        }
+      }
+    }
+  )code",
+                         UnorderedElementsAre(Pair("check", "safe")));
+
+  ExpectLatticeChecksFor(R"code(
+    #include "unchecked_optional_access_test.h"
+
+    void target(bool b, $ns::$optional<int> opt) {
+      if (b && !opt.has_value()) return;
+      if (b) {
+        opt.value();
+        /*[[check]]*/
+      }
+    }
+  )code",
+                         UnorderedElementsAre(Pair("check", "safe")));
+
+  ExpectLatticeChecksFor(
+      R"code(
+    #include "unchecked_optional_access_test.h"
+
+    void target(bool b, $ns::$optional<int> opt) {
+      if (opt.has_value()) b = true;
+      if (b) {
+        opt.value();
+        /*[[check]]*/
+      }
+    }
+  )code",
+      UnorderedElementsAre(Pair("check", "unsafe: input.cc:7:9")));
+
+  ExpectLatticeChecksFor(R"code(
+    #include "unchecked_optional_access_test.h"
+
+    void target(bool b, $ns::$optional<int> opt) {
+      if (b) return;
+      if (opt.has_value()) b = true;
+      if (b) {
+        opt.value();
+        /*[[check]]*/
+      }
+    }
+  )code",
+                         UnorderedElementsAre(Pair("check", "safe")));
+
+  ExpectLatticeChecksFor(R"(
+    #include "unchecked_optional_access_test.h"
+
+    void target(bool b, $ns::$optional<int> opt) {
+      if (opt.has_value() == b) {
+        if (b) {
+          opt.value();
+          /*[[check]]*/
+        }
+      }
+    }
+  )",
+                         UnorderedElementsAre(Pair("check", "safe")));
+
+  ExpectLatticeChecksFor(R"(
+    #include "unchecked_optional_access_test.h"
+
+    void target(bool b, $ns::$optional<int> opt) {
+      if (opt.has_value() != b) {
+        if (!b) {
+          opt.value();
+          /*[[check]]*/
+        }
+      }
+    }
+  )",
+                         UnorderedElementsAre(Pair("check", "safe")));
+
+  // FIXME: Add support for operator==.
+  // ExpectLatticeChecksFor(R"(
+  //   #include "unchecked_optional_access_test.h"
+  //
+  //   void target($ns::$optional<int> opt1, $ns::$optional<int> opt2) {
+  //     if (opt1 == opt2) {
+  //       if (opt1.has_value()) {
+  //         opt2.value();
+  //         /*[[check]]*/
+  //       }
+  //     }
+  //   }
+  // )",
+  //                     UnorderedElementsAre(Pair("check", "safe")));
+}
+
 // FIXME: Add support for:
 // - constructors (copy, move)
 // - assignment operators (default, copy, move)