diff --git a/flang-rt/include/flang-rt/runtime/format.h b/flang-rt/include/flang-rt/runtime/format.h
index b169d63fa4999..9469cb0ee9a4c 100644
--- a/flang-rt/include/flang-rt/runtime/format.h
+++ b/flang-rt/include/flang-rt/runtime/format.h
@@ -25,6 +25,8 @@ class Descriptor;
 
 namespace Fortran::runtime::io {
 
+RT_OFFLOAD_API_GROUP_BEGIN
+
 class IoStatementState;
 
 enum EditingFlags {
@@ -200,5 +202,8 @@ template <typename CONTEXT> class FormatControl {
   // must be last, may be incomplete
   Iteration stack_[maxMaxHeight];
 };
+
+RT_OFFLOAD_API_GROUP_END
+
 } // namespace Fortran::runtime::io
 #endif // FLANG_RT_RUNTIME_FORMAT_H_
diff --git a/flang-rt/include/flang-rt/runtime/internal-unit.h b/flang-rt/include/flang-rt/runtime/internal-unit.h
index 429d3489e0112..a046764153ad8 100644
--- a/flang-rt/include/flang-rt/runtime/internal-unit.h
+++ b/flang-rt/include/flang-rt/runtime/internal-unit.h
@@ -18,6 +18,8 @@
 
 namespace Fortran::runtime::io {
 
+RT_OFFLOAD_API_GROUP_BEGIN
+
 class IoErrorHandler;
 
 // Points to (but does not own) a CHARACTER scalar or array for internal I/O.
@@ -55,5 +57,8 @@ template <Direction DIR> class InternalDescriptorUnit : public ConnectionState {
 
 extern template class InternalDescriptorUnit<Direction::Output>;
 extern template class InternalDescriptorUnit<Direction::Input>;
+
+RT_OFFLOAD_API_GROUP_END
+
 } // namespace Fortran::runtime::io
 #endif // FLANG_RT_RUNTIME_INTERNAL_UNIT_H_
diff --git a/flang-rt/include/flang-rt/runtime/io-stmt.h b/flang-rt/include/flang-rt/runtime/io-stmt.h
index 73c59b0b5ed29..bfd5f69c76337 100644
--- a/flang-rt/include/flang-rt/runtime/io-stmt.h
+++ b/flang-rt/include/flang-rt/runtime/io-stmt.h
@@ -28,6 +28,8 @@
 
 namespace Fortran::runtime::io {
 
+RT_OFFLOAD_API_GROUP_BEGIN
+
 class ExternalFileUnit;
 class ChildIo;
 
@@ -880,5 +882,7 @@ class ErroneousIoStatementState : public IoStatementBase {
   ExternalFileUnit *unit_{nullptr};
 };
 
+RT_OFFLOAD_API_GROUP_END
+
 } // namespace Fortran::runtime::io
 #endif // FLANG_RT_RUNTIME_IO_STMT_H_
diff --git a/flang-rt/include/flang-rt/runtime/non-tbp-dio.h b/flang-rt/include/flang-rt/runtime/non-tbp-dio.h
index 2bbbfa7f97f79..99d4113b6c7a8 100644
--- a/flang-rt/include/flang-rt/runtime/non-tbp-dio.h
+++ b/flang-rt/include/flang-rt/runtime/non-tbp-dio.h
@@ -32,6 +32,8 @@ class DerivedType;
 
 namespace Fortran::runtime::io {
 
+RT_OFFLOAD_API_GROUP_BEGIN
+
 struct NonTbpDefinedIo {
   const typeInfo::DerivedType &derivedType;
   void (*subroutine)(); // null means no non-TBP defined I/O here
@@ -52,5 +54,7 @@ struct NonTbpDefinedIoTable {
   bool ignoreNonTbpEntries{false};
 };
 
+RT_OFFLOAD_API_GROUP_END
+
 } // namespace Fortran::runtime::io
 #endif // FLANG_RT_RUNTIME_NON_TBP_DIO_H_
diff --git a/flang-rt/include/flang-rt/runtime/work-queue.h b/flang-rt/include/flang-rt/runtime/work-queue.h
index 0daa7bc4d3384..124a87a772bbe 100644
--- a/flang-rt/include/flang-rt/runtime/work-queue.h
+++ b/flang-rt/include/flang-rt/runtime/work-queue.h
@@ -74,6 +74,8 @@ namespace Fortran::runtime {
 class Terminator;
 class WorkQueue;
 
+RT_OFFLOAD_API_GROUP_BEGIN
+
 // Ticket worker base classes
 
 template <typename TICKET> class ImmediateTicketRunner {
@@ -361,6 +363,7 @@ class DescriptorIoTicket
       : ImmediateTicketRunner<DescriptorIoTicket>(*this),
         Elementwise{descriptor}, io_{io}, table_{table},
         anyIoTookPlace_{anyIoTookPlace} {}
+
   RT_API_ATTRS int Begin(WorkQueue &);
   RT_API_ATTRS int Continue(WorkQueue &);
   RT_API_ATTRS bool &anyIoTookPlace() { return anyIoTookPlace_; }
@@ -551,5 +554,7 @@ class WorkQueue {
   TicketList *firstFree_{static_};
 };
 
+RT_OFFLOAD_API_GROUP_END
+
 } // namespace Fortran::runtime
 #endif // FLANG_RT_RUNTIME_WORK_QUEUE_H_
diff --git a/flang-rt/lib/runtime/edit-input.h b/flang-rt/lib/runtime/edit-input.h
index 686cd461b3e34..961f06569aca3 100644
--- a/flang-rt/lib/runtime/edit-input.h
+++ b/flang-rt/lib/runtime/edit-input.h
@@ -15,6 +15,8 @@
 
 namespace Fortran::runtime::io {
 
+RT_OFFLOAD_API_GROUP_BEGIN
+
 RT_API_ATTRS bool EditIntegerInput(
     IoStatementState &, const DataEdit &, void *, int kind, bool isSigned);
 
@@ -49,5 +51,7 @@ extern template RT_API_ATTRS bool EditCharacterInput(
 extern template RT_API_ATTRS bool EditCharacterInput(
     IoStatementState &, const DataEdit &, char32_t *, std::size_t);
 
+RT_OFFLOAD_API_GROUP_END
+
 } // namespace Fortran::runtime::io
 #endif // FLANG_RT_RUNTIME_EDIT_INPUT_H_
diff --git a/flang-rt/lib/runtime/edit-output.h b/flang-rt/lib/runtime/edit-output.h
index 51a47405e49e4..dbeccb291d363 100644
--- a/flang-rt/lib/runtime/edit-output.h
+++ b/flang-rt/lib/runtime/edit-output.h
@@ -25,6 +25,8 @@
 
 namespace Fortran::runtime::io {
 
+RT_OFFLOAD_API_GROUP_BEGIN
+
 // I, B, O, Z, and G output editing for INTEGER.
 // The DataEdit reference is const here (and elsewhere in this header) so that
 // one edit descriptor with a repeat factor may safely serve to edit
@@ -137,5 +139,7 @@ extern template class RealOutputEditing<10>;
 // TODO: double/double
 extern template class RealOutputEditing<16>;
 
+RT_OFFLOAD_API_GROUP_END
+
 } // namespace Fortran::runtime::io
 #endif // FLANG_RT_RUNTIME_EDIT_OUTPUT_H_
diff --git a/flang-rt/lib/runtime/unit.h b/flang-rt/lib/runtime/unit.h
index 86e5639f1250e..9aec9b1659576 100644
--- a/flang-rt/lib/runtime/unit.h
+++ b/flang-rt/lib/runtime/unit.h
@@ -46,6 +46,8 @@ extern RT_VAR_ATTRS ExternalFileUnit *defaultOutput; // unit 6
 extern RT_VAR_ATTRS ExternalFileUnit *errorOutput; // unit 0 extension
 RT_OFFLOAD_VAR_GROUP_END
 
+RT_OFFLOAD_API_GROUP_BEGIN
+
 #if defined(RT_USE_PSEUDO_FILE_UNIT)
 // A flavor of OpenFile class that pretends to be a terminal,
 // and only provides basic buffering of the output
@@ -298,5 +300,7 @@ class ChildIo {
   Fortran::common::optional<IoStatementState> io_;
 };
 
+RT_OFFLOAD_API_GROUP_END
+
 } // namespace Fortran::runtime::io
 #endif // FLANG_RT_RUNTIME_UNIT_H_
diff --git a/flang/include/flang/Decimal/decimal.h b/flang/include/flang/Decimal/decimal.h
index 443163d058e28..5e81e47a18268 100644
--- a/flang/include/flang/Decimal/decimal.h
+++ b/flang/include/flang/Decimal/decimal.h
@@ -65,6 +65,9 @@ enum DecimalConversionFlags {
 #define EXTRA_DECIMAL_CONVERSION_SPACE (1 + 1 + 2 * 16 - 1)
 
 #ifdef __cplusplus
+
+RT_OFFLOAD_API_GROUP_BEGIN
+
 template <int PREC>
 RT_API_ATTRS ConversionToDecimalResult ConvertToDecimal(char *, size_t,
     DecimalConversionFlags, int digits, enum FortranRounding rounding,
@@ -110,6 +113,9 @@ extern template RT_API_ATTRS ConversionToBinaryResult<64> ConvertToBinary<64>(
     const char *&, enum FortranRounding, const char *end);
 extern template RT_API_ATTRS ConversionToBinaryResult<113> ConvertToBinary<113>(
     const char *&, enum FortranRounding, const char *end);
+
+RT_OFFLOAD_API_GROUP_END
+
 } // namespace Fortran::decimal
 extern "C" {
 #define NS(x) Fortran::decimal::x