diff --git a/flang/lib/Lower/OpenMP.cpp b/flang/lib/Lower/OpenMP.cpp
--- a/flang/lib/Lower/OpenMP.cpp
+++ b/flang/lib/Lower/OpenMP.cpp
@@ -789,7 +789,7 @@
 ///    1 * x = x
 static int getOperationIdentity(llvm::StringRef reductionOpName,
                                 mlir::Location loc) {
-  if (reductionOpName.contains("add"))
+  if (reductionOpName.contains("add") || reductionOpName.contains("subtract"))
     return 0;
   else if (reductionOpName.contains("multiply"))
     return 1;
@@ -840,6 +840,9 @@
   case Fortran::parser::DefinedOperator::IntrinsicOperator::Add:
     res = builder.create<mlir::arith::AddIOp>(loc, op1, op2);
     break;
+  case Fortran::parser::DefinedOperator::IntrinsicOperator::Subtract:
+    res = builder.create<mlir::arith::SubIOp>(loc, op1, op2);
+    break;
   case Fortran::parser::DefinedOperator::IntrinsicOperator::Multiply:
     res = builder.create<mlir::arith::MulIOp>(loc, op1, op2);
     break;
@@ -924,6 +927,9 @@
   case Fortran::parser::DefinedOperator::IntrinsicOperator::Add:
     reductionName = "add_reduction";
     break;
+  case Fortran::parser::DefinedOperator::IntrinsicOperator::Subtract:
+    reductionName = "subtract_reduction";
+    break;
   case Fortran::parser::DefinedOperator::IntrinsicOperator::Multiply:
     reductionName = "multiply_reduction";
     break;
@@ -1034,6 +1040,7 @@
                 redDefinedOp->u)};
         switch (intrinsicOp) {
         case Fortran::parser::DefinedOperator::IntrinsicOperator::Add:
+        case Fortran::parser::DefinedOperator::IntrinsicOperator::Subtract:
         case Fortran::parser::DefinedOperator::IntrinsicOperator::Multiply:
           break;
 
@@ -1677,6 +1684,7 @@
 
         switch (intrinsicOp) {
         case Fortran::parser::DefinedOperator::IntrinsicOperator::Add:
+        case Fortran::parser::DefinedOperator::IntrinsicOperator::Subtract:
         case Fortran::parser::DefinedOperator::IntrinsicOperator::Multiply:
           break;
         default: