diff --git a/flang/include/flang/Runtime/support.h b/flang/include/flang/Runtime/support.h
--- a/flang/include/flang/Runtime/support.h
+++ b/flang/include/flang/Runtime/support.h
@@ -11,6 +11,8 @@
 #define FORTRAN_RUNTIME_SUPPORT_H_
 
 #include "flang/Runtime/entry-names.h"
+#include <cstddef>
+#include <cstdint>
 
 namespace Fortran::runtime {
 
@@ -21,6 +23,56 @@
 // Predicate: is the storage described by a Descriptor contiguous in memory?
 bool RTNAME(IsContiguous)(const Descriptor &);
 
+/// Copy elements from \p source to a contiguous memory area denoted
+/// by \p destination. The caller must guarantee that the destination
+/// buffer is big enough to hold all elements from \p source, and also
+/// that its alignment satisfies the minimal alignment required
+/// for the elements of \p source. \p destByteSize is the size in bytes
+/// of the destination buffer, and is only used for checking for overflows
+/// of the buffer.
+/// The runtime implementation is optimized to make reads from \p source
+/// efficiently by identifying contiguity in the leading dimensions (if any).
+///
+/// The implementation assumes that \p source and \p destination elements'
+/// locations never overlap.
+void RTNAME(PackContiguous)(
+    void *destination, const Descriptor &source, std::size_t destByteSize);
+
+/// Copy element from contiguous memory area denoted by \p source into
+/// \p destination. The caller must guarantee that the source buffer
+/// contains enough elements to be copied into \p destination, and also
+/// that its alignment satisfies the minimal alignment required
+/// for the elements of \p destination. \p destByteSize is the size in bytes
+/// of the source buffer, and is only used for checking for overruns
+/// of the buffer.
+/// The runtime implementation is optimized to make writes into \p destination
+/// efficiently by identifying contiguity in the leading dimensions (if any).
+///
+/// The implementation assumes that \p source and \p destination elements'
+/// locations never overlap.
+void RTNAME(UnpackContiguous)(const Descriptor &destination, const void *source,
+    std::size_t sourceByteSize);
+
+/// If \p source specifies contiguous storage in memory, then
+/// the returned address matches source.base_addr, otherwise,
+/// if \p destination is not null, then the function copies
+/// all elements from \p source into the destination buffer
+/// and returns \p destination, otherwise, the function returns
+/// a pointer to newly allocated contiguous buffer containing
+/// all elements from \p source (e.g. copied with RTNAME(PackContiguous)).
+///
+/// If \p destination is not null, then the caller must guarantee
+/// that the destination buffer is big enough to hold all elements
+/// from \p source, and also that its alignment satisfies the minimal
+/// alignment required for the elements of \p source.
+/// \p destByteSize is the size in bytes of the destination buffer,
+/// and is only used for checking for overflows of the buffer.
+///
+/// \p shouldFree is set to 1, if the function allocates new memory,
+/// otherwise, it is set to 0.
+void *RTNAME(MakeContiguous)(void *destination, const Descriptor &source,
+    std::size_t destByteSize, std::uint8_t *shouldFree);
+
 } // extern "C"
 } // namespace Fortran::runtime
 #endif // FORTRAN_RUNTIME_SUPPORT_H_