diff --git a/flang-rt/lib/flang_rt/descriptor-io.h b/flang-rt/lib/flang_rt/descriptor-io.h
@@ -6,8 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef FORTRAN_FLANG_RT_DESCRIPTOR_IO_H_
-#define FORTRAN_FLANG_RT_DESCRIPTOR_IO_H_
+#ifndef FLANGRT_DESCRIPTOR_IO_H_
+#define FLANGRT_DESCRIPTOR_IO_H_
 
 // Implementation of I/O data list item transfers based on descriptors.
 // (All I/O items come through here so that the code is exercised for test;
@@ -16,7 +16,7 @@
 
 #include "edit-input.h"
 #include "edit-output.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "io-stmt.h"
 #include "namelist.h"
 #include "terminator.h"
@@ -608,4 +608,4 @@ static RT_API_ATTRS bool DescriptorIO(IoStatementState &io,
   return false;
 }
 } // namespace Fortran::runtime::io::descr
-#endif /* FORTRAN_FLANG_RT_DESCRIPTOR_IO_H_ */
+#endif /* FLANGRT_DESCRIPTOR_IO_H_ */
diff --git a/flang-rt/lib/flang_rt/descriptor.cpp b/flang-rt/lib/flang_rt/descriptor.cpp
@@ -6,10 +6,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "ISO_Fortran_util.h"
 #include "derived.h"
-#include "flang-rt/flang_rt/allocator-registry.h"
+#include "flang-rt/allocator-registry.h"
 #include "memory.h"
 #include "stat.h"
 #include "terminator.h"

diff --git a/flang-rt/lib/flang_rt/dot-product.cpp b/flang-rt/lib/flang_rt/dot-product.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "float.h"
 #include "terminator.h"
 #include "tools.h"

diff --git a/flang-rt/lib/flang_rt/execute.cpp b/flang-rt/lib/flang_rt/execute.cpp
@@ -8,7 +8,7 @@
 
 #include "flang/Runtime/execute.h"
 #include "environment.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "stat.h"
 #include "terminator.h"
 #include "tools.h"

diff --git a/flang-rt/lib/flang_rt/extensions.cpp b/flang-rt/lib/flang_rt/extensions.cpp
@@ -10,8 +10,8 @@
 // extensions that will eventually be implemented in Fortran.
 
 #include "flang/Runtime/extensions.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/io-api-funcs.h"
 #include "terminator.h"
 #include "tools.h"
 #include "flang/Runtime/command.h"

diff --git a/flang-rt/lib/flang_rt/file.cpp b/flang-rt/lib/flang_rt/file.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "file.h"
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/memory.h"
 #include "tools.h"
 #include "flang/Runtime/magic-numbers.h"
 #include <algorithm>

diff --git a/flang-rt/lib/flang_rt/file.h b/flang-rt/lib/flang_rt/file.h
@@ -8,10 +8,10 @@
 
 // Raw system I/O wrappers
 
-#ifndef FORTRAN_FLANG_RT_FILE_H_
-#define FORTRAN_FLANG_RT_FILE_H_
+#ifndef FLANGRT_FILE_H_
+#define FLANGRT_FILE_H_
 
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/memory.h"
 #include "io-error.h"
 #include "flang/Common/optional.h"
 #include <cinttypes>
@@ -113,4 +113,4 @@ RT_API_ATTRS bool MayWrite(const char *path);
 RT_API_ATTRS bool MayReadAndWrite(const char *path);
 RT_API_ATTRS std::int64_t SizeInBytes(const char *path);
 } // namespace Fortran::runtime::io
-#endif /* FORTRAN_FLANG_RT_FILE_H_ */
+#endif /* FLANGRT_FILE_H_ */
diff --git a/flang-rt/lib/flang_rt/inquiry.cpp b/flang-rt/lib/flang_rt/inquiry.cpp
@@ -11,7 +11,7 @@
 
 #include "flang/Runtime/inquiry.h"
 #include "copy.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "terminator.h"
 #include "tools.h"
 #include <algorithm>

diff --git a/flang-rt/lib/flang_rt/internal-unit.cpp b/flang-rt/lib/flang_rt/internal-unit.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "internal-unit.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "io-error.h"
 #include "flang/Runtime/freestanding-tools.h"
 #include <algorithm>

diff --git a/flang-rt/lib/flang_rt/internal-unit.h b/flang-rt/lib/flang_rt/internal-unit.h
@@ -8,11 +8,11 @@
 
 // Fortran internal I/O "units"
 
-#ifndef FORTRAN_FLANG_RT_INTERNAL_UNIT_H_
-#define FORTRAN_FLANG_RT_INTERNAL_UNIT_H_
+#ifndef FLANGRT_INTERNAL_UNIT_H_
+#define FLANGRT_INTERNAL_UNIT_H_
 
 #include "connection.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include <cinttypes>
 #include <type_traits>
 
@@ -56,4 +56,4 @@ template <Direction DIR> class InternalDescriptorUnit : public ConnectionState {
 extern template class InternalDescriptorUnit<Direction::Output>;
 extern template class InternalDescriptorUnit<Direction::Input>;
 } // namespace Fortran::runtime::io
-#endif /* FORTRAN_FLANG_RT_INTERNAL_UNIT_H_ */
+#endif /* FLANGRT_INTERNAL_UNIT_H_ */
diff --git a/flang-rt/lib/flang_rt/io-api-common.h b/flang-rt/lib/flang_rt/io-api-common.h
@@ -6,10 +6,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef FORTRAN_FLANG_RT_IO_API_COMMON_H_
-#define FORTRAN_FLANG_RT_IO_API_COMMON_H_
+#ifndef FLANGRT_IO_API_COMMON_H_
+#define FLANGRT_IO_API_COMMON_H_
 
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/io-api-funcs.h"
 #include "io-stmt.h"
 #include "terminator.h"
 #include "unit.h"
@@ -94,4 +94,4 @@ RT_API_ATTRS Cookie BeginExternalListIO(
 }
 
 } // namespace Fortran::runtime::io
-#endif /* FORTRAN_FLANG_RT_IO_API_COMMON_H_ */
+#endif /* FLANGRT_IO_API_COMMON_H_ */
diff --git a/flang-rt/lib/flang_rt/io-api-minimal.cpp b/flang-rt/lib/flang_rt/io-api-minimal.cpp
@@ -10,7 +10,7 @@
 // list-directed output (PRINT *) of intrinsic types.
 
 #include "edit-output.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/io-api-funcs.h"
 #include "format.h"
 #include "io-api-common.h"
 #include "io-stmt.h"

diff --git a/flang-rt/lib/flang_rt/io-api.cpp b/flang-rt/lib/flang_rt/io-api.cpp
@@ -17,9 +17,9 @@
 #include "edit-input.h"
 #include "edit-output.h"
 #include "environment.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/io-api-funcs.h"
+#include "flang-rt/memory.h"
 #include "format.h"
 #include "io-api-common.h"
 #include "io-stmt.h"

diff --git a/flang-rt/lib/flang_rt/io-error.h b/flang-rt/lib/flang_rt/io-error.h
@@ -12,11 +12,11 @@
 // IOSTAT error codes are raw errno values augmented with values for
 // Fortran-specific errors.
 
-#ifndef FORTRAN_FLANG_RT_IO_ERROR_H_
-#define FORTRAN_FLANG_RT_IO_ERROR_H_
+#ifndef FLANGRT_IO_ERROR_H_
+#define FLANGRT_IO_ERROR_H_
 
-#include "flang-rt/flang_rt/iostat-funcs.h"
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/iostat-funcs.h"
+#include "flang-rt/memory.h"
 #include "terminator.h"
 #include <cinttypes>
 
@@ -78,4 +78,4 @@ class IoErrorHandler : public Terminator {
 };
 
 } // namespace Fortran::runtime::io
-#endif /* FORTRAN_FLANG_RT_IO_ERROR_H_ */
+#endif /* FLANGRT_IO_ERROR_H_ */
diff --git a/flang-rt/lib/flang_rt/io-stmt.cpp b/flang-rt/lib/flang_rt/io-stmt.cpp
@@ -9,7 +9,7 @@
 #include "io-stmt.h"
 #include "connection.h"
 #include "emit-encoded.h"
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/memory.h"
 #include "format.h"
 #include "tools.h"
 #include "unit.h"

diff --git a/flang-rt/lib/flang_rt/io-stmt.h b/flang-rt/lib/flang_rt/io-stmt.h
@@ -8,13 +8,13 @@
 
 // Representations of the state of an I/O statement in progress
 
-#ifndef FORTRAN_FLANG_RT_IO_STMT_H_
-#define FORTRAN_FLANG_RT_IO_STMT_H_
+#ifndef FLANGRT_IO_STMT_H_
+#define FLANGRT_IO_STMT_H_
 
 #include "connection.h"
 #include "file.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/io-api-funcs.h"
 #include "format.h"
 #include "internal-unit.h"
 #include "io-error.h"
@@ -789,4 +789,4 @@ class ErroneousIoStatementState : public IoStatementBase {
 };
 
 } // namespace Fortran::runtime::io
-#endif /* FORTRAN_FLANG_RT_IO_STMT_H_ */
+#endif /* FLANGRT_IO_STMT_H_ */
diff --git a/flang-rt/lib/flang_rt/iostat.cpp b/flang-rt/lib/flang_rt/iostat.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/iostat-funcs.h"
+#include "flang-rt/iostat-funcs.h"
 
 namespace Fortran::runtime::io {
 RT_OFFLOAD_API_GROUP_BEGIN

diff --git a/flang-rt/lib/flang_rt/matmul-transpose.cpp b/flang-rt/lib/flang_rt/matmul-transpose.cpp
@@ -21,7 +21,7 @@
 // to use the faster BLAS routines.
 
 #include "flang/Runtime/matmul-transpose.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "terminator.h"
 #include "tools.h"
 #include "flang/Common/optional.h"

diff --git a/flang-rt/lib/flang_rt/matmul.cpp b/flang-rt/lib/flang_rt/matmul.cpp
@@ -20,7 +20,7 @@
 // Places where BLAS routines could be called are marked as TODO items.
 
 #include "flang/Runtime/matmul.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "terminator.h"
 #include "tools.h"
 #include "flang/Common/optional.h"

diff --git a/flang-rt/lib/flang_rt/memory.cpp b/flang-rt/lib/flang_rt/memory.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/memory.h"
 #include "terminator.h"
 #include "tools.h"
 #include "flang/Runtime/freestanding-tools.h"

diff --git a/flang-rt/lib/flang_rt/misc-intrinsic.cpp b/flang-rt/lib/flang_rt/misc-intrinsic.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Runtime/misc-intrinsic.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "terminator.h"
 #include "tools.h"
 #include "flang/Common/optional.h"

diff --git a/flang-rt/lib/flang_rt/namelist.cpp b/flang-rt/lib/flang_rt/namelist.cpp
@@ -9,7 +9,7 @@
 #include "namelist.h"
 #include "descriptor-io.h"
 #include "emit-encoded.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/io-api-funcs.h"
 #include "io-stmt.h"
 #include <algorithm>
 #include <cstring>

diff --git a/flang-rt/lib/flang_rt/random-templates.h b/flang-rt/lib/flang_rt/random-templates.h
@@ -6,10 +6,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef FORTRAN_FLANG_RT_RANDOM_TEMPLATES_H_
-#define FORTRAN_FLANG_RT_RANDOM_TEMPLATES_H_
+#ifndef FLANGRT_RANDOM_TEMPLATES_H_
+#define FLANGRT_RANDOM_TEMPLATES_H_
 
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "lock.h"
 #include "numeric-templates.h"
 #include "flang/Common/optional.h"
@@ -85,4 +85,4 @@ inline void Generate(const Descriptor &harvest) {
 
 } // namespace Fortran::runtime::random
 
-#endif /* FORTRAN_FLANG_RT_RANDOM_TEMPLATES_H_ */
+#endif /* FLANGRT_RANDOM_TEMPLATES_H_ */
diff --git a/flang-rt/lib/flang_rt/random.cpp b/flang-rt/lib/flang_rt/random.cpp
@@ -10,7 +10,7 @@
 // RANDOM_SEED.
 
 #include "flang/Runtime/random.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "lock.h"
 #include "random-templates.h"
 #include "terminator.h"

diff --git a/flang-rt/lib/flang_rt/reduce.cpp b/flang-rt/lib/flang_rt/reduce.cpp
@@ -9,7 +9,7 @@
 // REDUCE() implementation
 
 #include "flang/Runtime/reduce.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "reduction-templates.h"
 #include "terminator.h"
 #include "tools.h"

diff --git a/flang-rt/lib/flang_rt/reduction-templates.h b/flang-rt/lib/flang_rt/reduction-templates.h
@@ -18,10 +18,10 @@
 // * Character-valued reductions (MAXVAL & MINVAL) return arbitrary
 //   length results, dynamically allocated in a caller-supplied descriptor
 
-#ifndef FORTRAN_FLANG_RT_REDUCTION_TEMPLATES_H_
-#define FORTRAN_FLANG_RT_REDUCTION_TEMPLATES_H_
+#ifndef FLANGRT_REDUCTION_TEMPLATES_H_
+#define FLANGRT_REDUCTION_TEMPLATES_H_
 
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "numeric-templates.h"
 #include "terminator.h"
 #include "tools.h"
@@ -412,4 +412,4 @@ template <int KIND> struct Norm2Helper {
 };
 
 } // namespace Fortran::runtime
-#endif /* FORTRAN_FLANG_RT_REDUCTION_TEMPLATES_H_ */
+#endif /* FLANGRT_REDUCTION_TEMPLATES_H_ */
diff --git a/flang-rt/lib/flang_rt/reduction.cpp b/flang-rt/lib/flang_rt/reduction.cpp
@@ -14,7 +14,7 @@
 // NORM2, MAXLOC, MINLOC, MAXVAL, and MINVAL are in extrema.cpp.
 
 #include "flang/Runtime/reduction.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "reduction-templates.h"
 #include <cinttypes>
 

diff --git a/flang-rt/lib/flang_rt/stack.h b/flang-rt/lib/flang_rt/stack.h
@@ -10,10 +10,10 @@
 // It is a list based stack with dynamic allocation/deallocation
 // of the list nodes.
 
-#ifndef FORTRAN_FLANG_RT_STACK_H_
-#define FORTRAN_FLANG_RT_STACK_H_
+#ifndef FLANGRT_STACK_H_
+#define FLANGRT_STACK_H_
 
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/memory.h"
 #include "terminator.h"
 
 namespace Fortran::runtime {
@@ -133,4 +133,4 @@ template <typename T, unsigned N = 0> class Stack : public StackStorage<T, N> {
   Terminator &terminator_;
 };
 } // namespace Fortran::runtime
-#endif /* FORTRAN_FLANG_RT_STACK_H_ */
+#endif /* FLANGRT_STACK_H_ */
diff --git a/flang-rt/lib/flang_rt/stat.cpp b/flang-rt/lib/flang_rt/stat.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "stat.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "terminator.h"
 #include "tools.h"
 

diff --git a/flang-rt/lib/flang_rt/support.cpp b/flang-rt/lib/flang_rt/support.cpp
@@ -8,7 +8,7 @@
 
 #include "flang/Runtime/support.h"
 #include "ISO_Fortran_util.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "type-info.h"
 
 namespace Fortran::runtime {

diff --git a/flang-rt/lib/flang_rt/temporary-stack.cpp b/flang-rt/lib/flang_rt/temporary-stack.cpp
@@ -10,8 +10,8 @@
 // temporaries. For use in HLFIR lowering.
 
 #include "flang/Runtime/temporary-stack.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/memory.h"
 #include "terminator.h"
 #include "flang/Common/ISO_Fortran_binding_wrapper.h"
 #include "flang/Runtime/assign.h"

diff --git a/flang-rt/lib/flang_rt/time-intrinsic.cpp b/flang-rt/lib/flang_rt/time-intrinsic.cpp
@@ -9,7 +9,7 @@
 // Implements time-related intrinsic subroutines.
 
 #include "flang/Runtime/time-intrinsic.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "terminator.h"
 #include "tools.h"
 #include "flang/Runtime/cpp-type.h"

diff --git a/flang-rt/lib/flang_rt/tools.h b/flang-rt/lib/flang_rt/tools.h
@@ -6,11 +6,11 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef FORTRAN_FLANG_RT_TOOLS_H_
-#define FORTRAN_FLANG_RT_TOOLS_H_
+#ifndef FLANGRT_TOOLS_H_
+#define FLANGRT_TOOLS_H_
 
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/memory.h"
 #include "stat.h"
 #include "terminator.h"
 #include "flang/Common/optional.h"
@@ -535,4 +535,4 @@ RT_API_ATTRS void CreatePartialReductionResult(Descriptor &result,
     const char *intrinsic, TypeCode);
 
 } // namespace Fortran::runtime
-#endif /* FORTRAN_FLANG_RT_TOOLS_H_ */
+#endif /* FLANGRT_TOOLS_H_ */
diff --git a/flang-rt/lib/flang_rt/transformational.cpp b/flang-rt/lib/flang_rt/transformational.cpp
@@ -18,7 +18,7 @@
 
 #include "flang/Runtime/transformational.h"
 #include "copy.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "terminator.h"
 #include "tools.h"
 #include "flang/Common/float128.h"

diff --git a/flang-rt/lib/flang_rt/type-code.cpp b/flang-rt/lib/flang_rt/type-code.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/type-code.h"
 #include <cstdint>
 
 namespace Fortran::runtime {

diff --git a/flang-rt/lib/flang_rt/type-info.h b/flang-rt/lib/flang_rt/type-info.h
@@ -6,13 +6,13 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef FORTRAN_FLANG_RT_TYPE_INFO_H_
-#define FORTRAN_FLANG_RT_TYPE_INFO_H_
+#ifndef FLANGRT_TYPE_INFO_H_
+#define FLANGRT_TYPE_INFO_H_
 
 // A C++ perspective of the derived type description schemata in
 // flang/module/__fortran_type_info.f90.
 
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "terminator.h"
 #include "flang/Common/Fortran-consts.h"
 #include "flang/Common/bit-population-count.h"
@@ -321,4 +321,4 @@ class DerivedType {
 };
 
 } // namespace Fortran::runtime::typeInfo
-#endif /* FORTRAN_FLANG_RT_TYPE_INFO_H_ */
+#endif /* FLANGRT_TYPE_INFO_H_ */
diff --git a/flang-rt/lib/flang_rt/unit-map.h b/flang-rt/lib/flang_rt/unit-map.h
@@ -9,10 +9,10 @@
 // Maps Fortran unit numbers to their ExternalFileUnit instances.
 // A simple hash table with forward-linked chains per bucket.
 
-#ifndef FORTRAN_FLANG_RT_UNIT_MAP_H_
-#define FORTRAN_FLANG_RT_UNIT_MAP_H_
+#ifndef FLANGRT_UNIT_MAP_H_
+#define FLANGRT_UNIT_MAP_H_
 
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/memory.h"
 #include "lock.h"
 #include "unit.h"
 #include "flang/Common/fast-int-set.h"
@@ -100,4 +100,4 @@ class UnitMap {
   int emergencyNewUnit_{maxNewUnits_}; // not recycled
 };
 } // namespace Fortran::runtime::io
-#endif /* FORTRAN_FLANG_RT_UNIT_MAP_H_ */
+#endif /* FLANGRT_UNIT_MAP_H_ */
diff --git a/flang-rt/lib/flang_rt/unit.h b/flang-rt/lib/flang_rt/unit.h
@@ -8,14 +8,14 @@
 
 // Fortran external I/O units
 
-#ifndef FORTRAN_FLANG_RT_UNIT_H_
-#define FORTRAN_FLANG_RT_UNIT_H_
+#ifndef FLANGRT_UNIT_H_
+#define FLANGRT_UNIT_H_
 
 #include "buffer.h"
 #include "connection.h"
 #include "environment.h"
 #include "file.h"
-#include "flang-rt/flang_rt/memory.h"
+#include "flang-rt/memory.h"
 #include "format.h"
 #include "io-error.h"
 #include "io-stmt.h"
@@ -291,4 +291,4 @@ class ChildIo {
 };
 
 } // namespace Fortran::runtime::io
-#endif /* FORTRAN_FLANG_RT_UNIT_H_ */
+#endif /* FLANGRT_UNIT_H_ */
diff --git a/flang-rt/unittests/Evaluate/ISO-Fortran-binding.cpp b/flang-rt/unittests/Evaluate/ISO-Fortran-binding.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "flang/Common/ISO_Fortran_binding_wrapper.h"
 #include "flang/Testing/testing.h"
 #include "llvm/Support/raw_ostream.h"

diff --git a/flang-rt/unittests/Evaluate/reshape.cpp b/flang-rt/unittests/Evaluate/reshape.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "flang/Runtime/transformational.h"
 #include "flang/Testing/testing.h"
 #include <cinttypes>

diff --git a/flang-rt/unittests/Runtime/ArrayConstructor.cpp b/flang-rt/unittests/Runtime/ArrayConstructor.cpp
@@ -6,9 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/array-constructor.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/array-constructor.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/type-code.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 #include "flang/Runtime/allocatable.h"

diff --git a/flang-rt/unittests/Runtime/CUDA/AllocatorCUF.cpp b/flang-rt/unittests/Runtime/CUDA/AllocatorCUF.cpp
@@ -7,11 +7,11 @@
 //===----------------------------------------------------------------------===//
 
 #include "cuda_runtime.h"
-#include "flang-rt/flang_rt/allocator-registry.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/CUDA/allocator.h"
+#include "flang-rt/allocator-registry.h"
+#include "flang-rt/descriptor.h"
 #include "gtest/gtest.h"
 #include "../../../lib/flang_rt/terminator.h"
-#include "flang-rt/CufRuntime/allocator.h"
 #include "flang/Runtime/CUDA/descriptor.h"
 #include "flang/Runtime/allocatable.h"
 #include "flang/Support/Fortran.h"

diff --git a/flang-rt/unittests/Runtime/CharacterTest.cpp b/flang-rt/unittests/Runtime/CharacterTest.cpp
@@ -10,7 +10,7 @@
 // in Fortran.
 
 #include "flang/Runtime/character.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "gtest/gtest.h"
 #include <cstring>
 #include <functional>

diff --git a/flang-rt/unittests/Runtime/CommandTest.cpp b/flang-rt/unittests/Runtime/CommandTest.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Runtime/command.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "flang/Runtime/execute.h"

diff --git a/flang-rt/unittests/Runtime/Derived.cpp b/flang-rt/unittests/Runtime/Derived.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 #include "flang/Runtime/derived-api.h"

diff --git a/flang-rt/unittests/Runtime/ExternalIOTest.cpp b/flang-rt/unittests/Runtime/ExternalIOTest.cpp
@@ -11,8 +11,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "CrashHandlerFixture.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/io-api-funcs.h"
 #include "gtest/gtest.h"
 #include "flang/Runtime/main.h"
 #include "flang/Runtime/stop.h"

diff --git a/flang-rt/unittests/Runtime/Inquiry.cpp b/flang-rt/unittests/Runtime/Inquiry.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Runtime/inquiry.h"
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/type-code.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 

diff --git a/flang-rt/unittests/Runtime/ListInputTest.cpp b/flang-rt/unittests/Runtime/ListInputTest.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "CrashHandlerFixture.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/io-api-funcs.h"
 #include "../../lib/flang_rt/io-error.h"
 
 using namespace Fortran::runtime;

diff --git a/flang-rt/unittests/Runtime/LogicalFormatTest.cpp b/flang-rt/unittests/Runtime/LogicalFormatTest.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "CrashHandlerFixture.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/io-api-funcs.h"
 #include <algorithm>
 #include <array>
 #include <cstring>

diff --git a/flang-rt/unittests/Runtime/Matmul.cpp b/flang-rt/unittests/Runtime/Matmul.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Runtime/matmul.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/type-code.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 #include "flang/Runtime/allocatable.h"

diff --git a/flang-rt/unittests/Runtime/MatmulTranspose.cpp b/flang-rt/unittests/Runtime/MatmulTranspose.cpp
@@ -6,8 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/type-code.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 #include "flang/Runtime/allocatable.h"

diff --git a/flang-rt/unittests/Runtime/MiscIntrinsic.cpp b/flang-rt/unittests/Runtime/MiscIntrinsic.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 #include "flang/Runtime/allocatable.h"

diff --git a/flang-rt/unittests/Runtime/Namelist.cpp b/flang-rt/unittests/Runtime/Namelist.cpp
@@ -8,8 +8,8 @@
 
 #include "../../lib/flang_rt/namelist.h"
 #include "CrashHandlerFixture.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/io-api-funcs.h"
 #include "tools.h"
 #include <algorithm>
 #include <cinttypes>

diff --git a/flang-rt/unittests/Runtime/NumericalFormatTest.cpp b/flang-rt/unittests/Runtime/NumericalFormatTest.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "CrashHandlerFixture.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/io-api-funcs.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/io-api-funcs.h"
 #include <algorithm>
 #include <array>
 #include <cstring>

diff --git a/flang-rt/unittests/Runtime/Pointer.cpp b/flang-rt/unittests/Runtime/Pointer.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Runtime/pointer.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 

diff --git a/flang-rt/unittests/Runtime/Random.cpp b/flang-rt/unittests/Runtime/Random.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Runtime/random.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/type-code.h"
 #include "gtest/gtest.h"
 #include <cmath>
 

diff --git a/flang-rt/unittests/Runtime/Reduction.cpp b/flang-rt/unittests/Runtime/Reduction.cpp
@@ -7,8 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Runtime/reduction.h"
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/type-code.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 #include "flang/Common/float128.h"

diff --git a/flang-rt/unittests/Runtime/Support.cpp b/flang-rt/unittests/Runtime/Support.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Runtime/support.h"
-#include "flang-rt/flang_rt/descriptor.h"
+#include "flang-rt/descriptor.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 

diff --git a/flang-rt/unittests/Runtime/TemporaryStack.cpp b/flang-rt/unittests/Runtime/TemporaryStack.cpp
@@ -6,8 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/type-code.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 #include "flang/Common/ISO_Fortran_binding_wrapper.h"

diff --git a/flang-rt/unittests/Runtime/Transformational.cpp b/flang-rt/unittests/Runtime/Transformational.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Runtime/transformational.h"
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/type-code.h"
 #include "gtest/gtest.h"
 #include "tools.h"
 #include "flang/Common/float128.h"

diff --git a/flang-rt/unittests/Runtime/tools.h b/flang-rt/unittests/Runtime/tools.h
@@ -6,11 +6,11 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef FORTRAN_UNITTESTS_RUNTIME_TOOLS_H_
-#define FORTRAN_UNITTESTS_RUNTIME_TOOLS_H_
+#ifndef FLANGRT_UNITTESTS_RUNTIME_TOOLS_H_
+#define FLANGRT_UNITTESTS_RUNTIME_TOOLS_H_
 
-#include "flang-rt/flang_rt/descriptor.h"
-#include "flang-rt/flang_rt/type-code.h"
+#include "flang-rt/descriptor.h"
+#include "flang-rt/type-code.h"
 #include "gtest/gtest.h"
 #include "flang/Runtime/allocatable.h"
 #include "flang/Runtime/cpp-type.h"
@@ -54,4 +54,4 @@ static OwningPtr<Descriptor> MakeArray(const std::vector<int> &shape,
 }
 
 } // namespace Fortran::runtime
-#endif /* FORTRAN_UNITTESTS_RUNTIME_TOOLS_H_ */
+#endif /* FLANGRT_UNITTESTS_RUNTIME_TOOLS_H_ */
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
@@ -144,6 +144,12 @@ if ("flang" IN_LIST LLVM_ENABLE_PROJECTS)
   endif()
 endif()
 
+if ("flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
+  if (NOT "flang" IN_LIST LLVM_ENABLE_PROJECTS)
+    message(FATAL_ERROR "Flang is not enabled, but is required for the Flang-RT runtime")
+  endif ()
+endif ()
+
 # Select the runtimes to build
 #
 # As we migrate runtimes to using the bootstrapping build, the set of default runtimes

diff --git a/llvm/runtimes/CMakeLists.txt b/llvm/runtimes/CMakeLists.txt
@@ -137,7 +137,6 @@ function(builtin_register_target compiler_rt_path name)
                                       -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON
                                       -DLLVM_CMAKE_DIR=${CMAKE_BINARY_DIR}
                                       -DCMAKE_C_COMPILER_WORKS=ON
-                                      -DCMAKE_Fortran_COMPILER_WORKS=ON
                                       -DCMAKE_ASM_COMPILER_WORKS=ON
                                       -DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON
                                       ${COMMON_CMAKE_ARGS}
@@ -232,7 +231,7 @@ foreach(entry ${runtimes})
 endforeach()
 
 function(runtime_default_target)
-  cmake_parse_arguments(ARG "" "" "DEPENDS;CMAKE_ARGS;PREFIXES" ${ARGN})
+  cmake_parse_arguments(ARG "" "" "DEPENDS;CMAKE_ARGS;PREFIXES;EXTRA_ARGS" ${ARGN})
 
   include(${LLVM_BINARY_DIR}/runtimes/Components.cmake OPTIONAL)
   set(SUB_CHECK_TARGETS ${SUB_CHECK_TARGETS} PARENT_SCOPE)
@@ -263,7 +262,6 @@ function(runtime_default_target)
   llvm_ExternalProject_Add(runtimes
                            ${CMAKE_CURRENT_SOURCE_DIR}/../../runtimes
                            DEPENDS ${ARG_DEPENDS}
-                           ${enable_fortran}
                            # Builtins were built separately above
                            CMAKE_ARGS -DCOMPILER_RT_BUILD_BUILTINS=Off
                                       -DLLVM_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
@@ -291,7 +289,7 @@ function(runtime_default_target)
                            USE_TOOLCHAIN
                            TARGET_TRIPLE ${LLVM_TARGET_TRIPLE}
                            FOLDER "Runtimes"
-                           ${EXTRA_ARGS})
+                           ${EXTRA_ARGS} ${ARG_EXTRA_ARGS})
 endfunction()
 
 # runtime_register_target(name)
@@ -401,7 +399,6 @@ function(runtime_register_target name)
   llvm_ExternalProject_Add(runtimes-${name}
                            ${CMAKE_CURRENT_SOURCE_DIR}/../../runtimes
                            DEPENDS ${ARG_DEPENDS}
-                           ${enable_fortran}
                            # Builtins were built separately above
                            CMAKE_ARGS -DCOMPILER_RT_BUILD_BUILTINS=OFF
                                       -DLLVM_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
@@ -469,7 +466,7 @@ if(build_runtimes)
   # together in a single CMake invocation.
   set(extra_deps "")
   set(extra_cmake_args "")
-  set(enable_fortran "")
+  set(extra_args "")
 
   if(LLVM_INCLUDE_TESTS)
     foreach(dep FileCheck
@@ -574,21 +571,23 @@ if(build_runtimes)
     list(APPEND extra_cmake_args "-DLLVM_LIBC_FULL_BUILD=ON")
   endif()
   if("flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
-    set(enable_fortran ENABLE_FORTRAN)
+    list(APPEND extra_args ENABLE_FORTRAN)
   endif ()
 
   if(NOT LLVM_RUNTIME_TARGETS)
     runtime_default_target(
       DEPENDS ${builtins_dep} ${extra_deps}
       CMAKE_ARGS ${extra_cmake_args}
-      PREFIXES ${prefixes})
+      PREFIXES ${prefixes}
+      EXTRA_ARGS ${extra_args})
     set(test_targets check-runtimes)
   else()
     if("default" IN_LIST LLVM_RUNTIME_TARGETS)
       runtime_default_target(
         DEPENDS ${builtins_dep} ${extra_deps}
         CMAKE_ARGS ${extra_cmake_args}
-        PREFIXES ${prefixes})
+        PREFIXES ${prefixes}
+        EXTRA_ARGS ${extra_args})
       list(REMOVE_ITEM LLVM_RUNTIME_TARGETS "default")
     else()
       add_custom_target(runtimes)
@@ -635,7 +634,7 @@ if(build_runtimes)
       runtime_register_target(${name}
         DEPENDS ${builtins_dep_name} ${extra_deps}
         CMAKE_ARGS -DLLVM_DEFAULT_TARGET_TRIPLE=${name} ${extra_cmake_args}
-        EXTRA_ARGS TARGET_TRIPLE ${name})
+        EXTRA_ARGS TARGET_TRIPLE ${name} ${extra_args})
     endforeach()
 
     foreach(multilib ${LLVM_RUNTIME_MULTILIBS})
@@ -646,7 +645,7 @@ if(build_runtimes)
                      -DLLVM_RUNTIMES_PREFIX=${name}/
                      -DLLVM_RUNTIMES_LIBDIR_SUBDIR=${multilib}
           BASE_NAME ${name}
-          EXTRA_ARGS TARGET_TRIPLE ${name})
+          EXTRA_ARGS TARGET_TRIPLE ${name} ${extra_args})
       endforeach()
     endforeach()
   endif()