diff --git a/flang/include/flang/Optimizer/Builder/Complex.h b/flang/include/flang/Optimizer/Builder/Complex.h
new file mode 100644
--- /dev/null
+++ b/flang/include/flang/Optimizer/Builder/Complex.h
@@ -0,0 +1,88 @@
+//===-- Complex.h -- lowering of complex values -----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Coding style: https://mlir.llvm.org/getting_started/DeveloperGuide/
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef FORTRAN_OPTIMIZER_BUILDER_COMPLEX_H
+#define FORTRAN_OPTIMIZER_BUILDER_COMPLEX_H
+
+#include "flang/Optimizer/Builder/FIRBuilder.h"
+
+namespace fir::factory {
+
+/// Helper to facilitate lowering of COMPLEX manipulations in FIR.
+class Complex {
+public:
+  explicit Complex(FirOpBuilder &builder, mlir::Location loc)
+      : builder(builder), loc(loc) {}
+  Complex(const Complex &) = delete;
+
+  // The values of part enum members are meaningful for
+  // InsertValueOp and ExtractValueOp so they are explicit.
+  enum class Part { Real = 0, Imag = 1 };
+
+  /// Get the Complex Type. Determine the type. Do not create MLIR operations.
+  mlir::Type getComplexPartType(mlir::Value cplx);
+  mlir::Type getComplexPartType(mlir::Type complexType);
+
+  /// Complex operation creation. They create MLIR operations.
+  mlir::Value createComplex(fir::KindTy kind, mlir::Value real,
+                            mlir::Value imag);
+
+  /// Create a complex value.
+  mlir::Value createComplex(mlir::Type complexType, mlir::Value real,
+                            mlir::Value imag);
+
+  mlir::Value extractComplexPart(mlir::Value cplx, bool isImagPart) {
+    return isImagPart ? extract<Part::Imag>(cplx) : extract<Part::Real>(cplx);
+  }
+
+  /// Returns (Real, Imag) pair of \p cplx
+  std::pair<mlir::Value, mlir::Value> extractParts(mlir::Value cplx) {
+    return {extract<Part::Real>(cplx), extract<Part::Imag>(cplx)};
+  }
+
+  mlir::Value insertComplexPart(mlir::Value cplx, mlir::Value part,
+                                bool isImagPart) {
+    return isImagPart ? insert<Part::Imag>(cplx, part)
+                      : insert<Part::Real>(cplx, part);
+  }
+
+protected:
+  template <Part partId>
+  mlir::Value extract(mlir::Value cplx) {
+    return builder.create<fir::ExtractValueOp>(
+        loc, getComplexPartType(cplx), cplx,
+        builder.getArrayAttr({builder.getIntegerAttr(
+            builder.getIndexType(), static_cast<int>(partId))}));
+  }
+
+  template <Part partId>
+  mlir::Value insert(mlir::Value cplx, mlir::Value part) {
+    return builder.create<fir::InsertValueOp>(
+        loc, cplx.getType(), cplx, part,
+        builder.getArrayAttr({builder.getIntegerAttr(
+            builder.getIndexType(), static_cast<int>(partId))}));
+  }
+
+  template <Part partId>
+  mlir::Value createPartId() {
+    return builder.createIntegerConstant(loc, builder.getIndexType(),
+                                         static_cast<int>(partId));
+  }
+
+private:
+  FirOpBuilder &builder;
+  mlir::Location loc;
+};
+
+} // namespace fir::factory
+
+#endif // FORTRAN_OPTIMIZER_BUILDER_COMPLEX_H
diff --git a/flang/include/flang/Optimizer/Builder/FIRBuilder.h b/flang/include/flang/Optimizer/Builder/FIRBuilder.h
--- a/flang/include/flang/Optimizer/Builder/FIRBuilder.h
+++ b/flang/include/flang/Optimizer/Builder/FIRBuilder.h
@@ -57,6 +57,13 @@
   /// Get a reference to the kind map.
   const fir::KindMapping &getKindMap() { return kindMap; }
 
+  /// The LHS and RHS are not always in agreement in terms of
+  /// type. In some cases, the disagreement is between COMPLEX and other scalar
+  /// types. In that case, the conversion must insert/extract out of a COMPLEX
+  /// value to have the proper semantics and be strongly typed.
+  mlir::Value convertWithSemantics(mlir::Location loc, mlir::Type toTy,
+                                   mlir::Value val);
+
   /// Get the entry block of the current Function
   mlir::Block *getEntryBlock() { return &getFunction().front(); }
 
diff --git a/flang/lib/Optimizer/Builder/CMakeLists.txt b/flang/lib/Optimizer/Builder/CMakeLists.txt
--- a/flang/lib/Optimizer/Builder/CMakeLists.txt
+++ b/flang/lib/Optimizer/Builder/CMakeLists.txt
@@ -3,6 +3,7 @@
 add_flang_library(FIRBuilder
   BoxValue.cpp
   Character.cpp
+  Complex.cpp
   DoLoopHelper.cpp
   FIRBuilder.cpp
   MutableBox.cpp
diff --git a/flang/lib/Optimizer/Builder/Complex.cpp b/flang/lib/Optimizer/Builder/Complex.cpp
new file mode 100644
--- /dev/null
+++ b/flang/lib/Optimizer/Builder/Complex.cpp
@@ -0,0 +1,36 @@
+//===-- Complex.cpp -------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "flang/Optimizer/Builder/Complex.h"
+
+//===----------------------------------------------------------------------===//
+// Complex Factory implementation
+//===----------------------------------------------------------------------===//
+
+mlir::Type fir::factory::Complex::getComplexPartType(mlir::Type complexType) {
+  return builder.getRealType(complexType.cast<fir::ComplexType>().getFKind());
+}
+
+mlir::Type fir::factory::Complex::getComplexPartType(mlir::Value cplx) {
+  return getComplexPartType(cplx.getType());
+}
+
+mlir::Value fir::factory::Complex::createComplex(fir::KindTy kind,
+                                                 mlir::Value real,
+                                                 mlir::Value imag) {
+  auto complexTy = fir::ComplexType::get(builder.getContext(), kind);
+  mlir::Value und = builder.create<fir::UndefOp>(loc, complexTy);
+  return insert<Part::Imag>(insert<Part::Real>(und, real), imag);
+}
+
+mlir::Value fir::factory::Complex::createComplex(mlir::Type cplxTy,
+                                                 mlir::Value real,
+                                                 mlir::Value imag) {
+  mlir::Value und = builder.create<fir::UndefOp>(loc, cplxTy);
+  return insert<Part::Imag>(insert<Part::Real>(und, real), imag);
+}
diff --git a/flang/lib/Optimizer/Builder/FIRBuilder.cpp b/flang/lib/Optimizer/Builder/FIRBuilder.cpp
--- a/flang/lib/Optimizer/Builder/FIRBuilder.cpp
+++ b/flang/lib/Optimizer/Builder/FIRBuilder.cpp
@@ -9,6 +9,7 @@
 #include "flang/Optimizer/Builder/FIRBuilder.h"
 #include "flang/Optimizer/Builder/BoxValue.h"
 #include "flang/Optimizer/Builder/Character.h"
+#include "flang/Optimizer/Builder/Complex.h"
 #include "flang/Optimizer/Builder/MutableBox.h"
 #include "flang/Optimizer/Dialect/FIROpsSupport.h"
 #include "flang/Optimizer/Support/FatalError.h"
@@ -257,6 +258,33 @@
   return glob;
 }
 
+mlir::Value fir::FirOpBuilder::convertWithSemantics(mlir::Location loc,
+                                                    mlir::Type toTy,
+                                                    mlir::Value val) {
+  assert(toTy && "store location must be typed");
+  auto fromTy = val.getType();
+  if (fromTy == toTy)
+    return val;
+  fir::factory::Complex helper{*this, loc};
+  if ((fir::isa_real(fromTy) || fir::isa_integer(fromTy)) &&
+      fir::isa_complex(toTy)) {
+    // imaginary part is zero
+    auto eleTy = helper.getComplexPartType(toTy);
+    auto cast = createConvert(loc, eleTy, val);
+    llvm::APFloat zero{
+        kindMap.getFloatSemantics(toTy.cast<fir::ComplexType>().getFKind()), 0};
+    auto imag = createRealConstant(loc, eleTy, zero);
+    return helper.createComplex(toTy, cast, imag);
+  }
+  if (fir::isa_complex(fromTy) &&
+      (fir::isa_integer(toTy) || fir::isa_real(toTy))) {
+    // drop the imaginary part
+    auto rp = helper.extractComplexPart(val, /*isImagPart=*/false);
+    return createConvert(loc, toTy, rp);
+  }
+  return createConvert(loc, toTy, val);
+}
+
 mlir::Value fir::FirOpBuilder::createConvert(mlir::Location loc,
                                              mlir::Type toTy, mlir::Value val) {
   if (val.getType() != toTy) {
diff --git a/flang/unittests/Optimizer/Builder/ComplexTest.cpp b/flang/unittests/Optimizer/Builder/ComplexTest.cpp
new file mode 100644
--- /dev/null
+++ b/flang/unittests/Optimizer/Builder/ComplexTest.cpp
@@ -0,0 +1,101 @@
+//===- ComplexExprTest.cpp -- ComplexExpr unit tests ----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "flang/Optimizer/Builder/Complex.h"
+#include "gtest/gtest.h"
+#include "flang/Optimizer/Builder/FIRBuilder.h"
+#include "flang/Optimizer/Support/InitFIR.h"
+#include "flang/Optimizer/Support/KindMapping.h"
+
+struct ComplexTest : public testing::Test {
+public:
+  void SetUp() override {
+    mlir::OpBuilder builder(&context);
+    auto loc = builder.getUnknownLoc();
+
+    // Set up a Module with a dummy function operation inside.
+    // Set the insertion point in the function entry block.
+    mlir::ModuleOp mod = builder.create<mlir::ModuleOp>(loc);
+    mlir::FuncOp func = mlir::FuncOp::create(
+        loc, "func1", builder.getFunctionType(llvm::None, llvm::None));
+    auto *entryBlock = func.addEntryBlock();
+    mod.push_back(mod);
+    builder.setInsertionPointToStart(entryBlock);
+
+    fir::support::loadDialects(context);
+    kindMap = std::make_unique<fir::KindMapping>(&context);
+    firBuilder = std::make_unique<fir::FirOpBuilder>(mod, *kindMap);
+    helper = std::make_unique<fir::factory::Complex>(*firBuilder, loc);
+
+    // Init commonly used types
+    realTy1 = mlir::FloatType::getF32(&context);
+    complexTy1 = fir::ComplexType::get(&context, 4);
+    integerTy1 = mlir::IntegerType::get(&context, 32);
+
+    // Create commonly used reals
+    rOne = firBuilder->createRealConstant(loc, realTy1, 1u);
+    rTwo = firBuilder->createRealConstant(loc, realTy1, 2u);
+    rThree = firBuilder->createRealConstant(loc, realTy1, 3u);
+    rFour = firBuilder->createRealConstant(loc, realTy1, 4u);
+  }
+
+
+  mlir::MLIRContext context;
+  std::unique_ptr<fir::KindMapping> kindMap;
+  std::unique_ptr<fir::FirOpBuilder> firBuilder;
+  std::unique_ptr<fir::factory::Complex> helper;
+
+  // Commonly used real/complex/integer types
+  mlir::FloatType realTy1;
+  fir::ComplexType complexTy1;
+  mlir::IntegerType integerTy1;
+
+  // Commonly used real numbers
+  mlir::Value rOne;
+  mlir::Value rTwo;
+  mlir::Value rThree;
+  mlir::Value rFour;
+};
+
+TEST_F(ComplexTest, verifyTypes) {
+  mlir::Value cVal1 = helper->createComplex(complexTy1, rOne, rTwo);
+  mlir::Value cVal2 = helper->createComplex(4, rOne, rTwo);
+  EXPECT_TRUE(fir::isa_complex(cVal1.getType()));
+  EXPECT_TRUE(fir::isa_complex(cVal2.getType()));
+  EXPECT_TRUE(fir::isa_real(helper->getComplexPartType(cVal1)));
+  EXPECT_TRUE(fir::isa_real(helper->getComplexPartType(cVal2)));
+
+  mlir::Value real1 = helper->extractComplexPart(cVal1, /*isImagPart=*/false);
+  mlir::Value imag1 = helper->extractComplexPart(cVal1, /*isImagPart=*/true);
+  mlir::Value real2 = helper->extractComplexPart(cVal2, /*isImagPart=*/false);
+  mlir::Value imag2 = helper->extractComplexPart(cVal2, /*isImagPart=*/true);
+  EXPECT_EQ(realTy1, real1.getType());
+  EXPECT_EQ(realTy1, imag1.getType());
+  EXPECT_EQ(realTy1, real2.getType());
+  EXPECT_EQ(realTy1, imag2.getType());
+
+  mlir::Value cVal3 =
+      helper->insertComplexPart(cVal1, rThree, /*isImagPart=*/false);
+  mlir::Value cVal4 =
+      helper->insertComplexPart(cVal3, rFour, /*isImagPart=*/true);
+  EXPECT_TRUE(fir::isa_complex(cVal4.getType()));
+  EXPECT_TRUE(fir::isa_real(helper->getComplexPartType(cVal4)));
+}
+
+TEST_F(ComplexTest, verifyConvertWithSemantics) {
+  auto loc = firBuilder->getUnknownLoc();
+  rOne = firBuilder->createRealConstant(loc, realTy1, 1u);
+  // Convert real to complex
+  mlir::Value v1 = firBuilder->convertWithSemantics(loc, complexTy1, rOne);
+  EXPECT_TRUE(fir::isa_complex(v1.getType()));
+
+  // Convert complex to integer
+  mlir::Value v2 = firBuilder->convertWithSemantics(loc, integerTy1, v1);
+  EXPECT_TRUE(v2.getType().isa<mlir::IntegerType>());
+  EXPECT_TRUE(mlir::dyn_cast<fir::ConvertOp>(v2.getDefiningOp()));
+}
diff --git a/flang/unittests/Optimizer/CMakeLists.txt b/flang/unittests/Optimizer/CMakeLists.txt
--- a/flang/unittests/Optimizer/CMakeLists.txt
+++ b/flang/unittests/Optimizer/CMakeLists.txt
@@ -10,6 +10,7 @@
 
 add_flang_unittest(FlangOptimizerTests
   Builder/CharacterTest.cpp
+  Builder/ComplexTest.cpp
   Builder/DoLoopHelperTest.cpp
   Builder/FIRBuilderTest.cpp
   FIRContextTest.cpp