diff --git a/flang/lib/Optimizer/Dialect/FIRDialect.cpp b/flang/lib/Optimizer/Dialect/FIRDialect.cpp
--- a/flang/lib/Optimizer/Dialect/FIRDialect.cpp
+++ b/flang/lib/Optimizer/Dialect/FIRDialect.cpp
@@ -14,9 +14,49 @@
 #include "flang/Optimizer/Dialect/FIRAttr.h"
 #include "flang/Optimizer/Dialect/FIROps.h"
 #include "flang/Optimizer/Dialect/FIRType.h"
+#include "mlir/Transforms/InliningUtils.h"
 
 using namespace fir;
 
+namespace {
+/// This class defines the interface for handling inlining of FIR calls.
+struct FIRInlinerInterface : public mlir::DialectInlinerInterface {
+  using DialectInlinerInterface::DialectInlinerInterface;
+
+  bool isLegalToInline(mlir::Operation *call, mlir::Operation *callable,
+                       bool wouldBeCloned) const final {
+    return fir::canLegallyInline(call, callable, wouldBeCloned);
+  }
+
+  /// This hook checks to see if the operation `op` is legal to inline into the
+  /// given region `reg`.
+  bool isLegalToInline(mlir::Operation *op, mlir::Region *reg,
+                       bool wouldBeCloned,
+                       mlir::BlockAndValueMapping &map) const final {
+    return fir::canLegallyInline(op, reg, wouldBeCloned, map);
+  }
+
+  /// This hook is called when a terminator operation has been inlined.
+  /// We handle the return (a Fortran FUNCTION) by replacing the values
+  /// previously returned by the call operation with the operands of the
+  /// return.
+  void handleTerminator(mlir::Operation *op,
+                        llvm::ArrayRef<mlir::Value> valuesToRepl) const final {
+    auto returnOp = cast<mlir::ReturnOp>(op);
+    assert(returnOp.getNumOperands() == valuesToRepl.size());
+    for (const auto &it : llvm::enumerate(returnOp.getOperands()))
+      valuesToRepl[it.index()].replaceAllUsesWith(it.value());
+  }
+
+  mlir::Operation *materializeCallConversion(mlir::OpBuilder &builder,
+                                             mlir::Value input,
+                                             mlir::Type resultType,
+                                             mlir::Location loc) const final {
+    return builder.create<fir::ConvertOp>(loc, resultType, input);
+  }
+};
+} // namespace
+
 fir::FIROpsDialect::FIROpsDialect(mlir::MLIRContext *ctx)
     : mlir::Dialect("fir", ctx, mlir::TypeID::get<FIROpsDialect>()) {
   registerTypes();
@@ -25,6 +65,7 @@
 #define GET_OP_LIST
 #include "flang/Optimizer/Dialect/FIROps.cpp.inc"
       >();
+  addInterfaces<FIRInlinerInterface>();
 }
 
 // anchor the class vtable to this compilation unit
diff --git a/flang/test/Fir/inline.fir b/flang/test/Fir/inline.fir
new file mode 100644
--- /dev/null
+++ b/flang/test/Fir/inline.fir
@@ -0,0 +1,19 @@
+// RUN: tco --target=x86_64-unknown-linux-gnu --inline-all %s -o - | FileCheck %s
+
+// CHECK-LABEL: @add
+func @add(%a : i32, %b : i32) -> i32 {
+  // CHECK: %[[add:.*]] = add i32
+  %p = arith.addi %a, %b : i32
+  // CHECK: ret i32 %[[add]]
+  return %p : i32
+}
+
+// CHECK-LABEL: @test
+func @test(%a : i32, %b : i32, %c : i32) -> i32 {
+  // CHECK: %[[add:.*]] = add i32
+  %m = fir.call @add(%a, %b) : (i32, i32) -> i32
+  // CHECK: %[[mul:.*]] = mul i32 %[[add]],
+  %n = arith.muli %m, %c : i32
+  // CHECK: ret i32 %[[mul]]
+  return %n : i32
+}