diff --git a/flang-rt/test/CMakeLists.txt b/flang-rt/test/CMakeLists.txt
diff --git a/flang-rt/test/FortranRuntime/no-cpp-dep.c b/flang-rt/test/FortranRuntime/no-cpp-dep.c
diff --git a/flang-rt/test/NonGtestUnit/lit.cfg.py b/flang-rt/test/NonGtestUnit/lit.cfg.py
diff --git a/flang-rt/test/NonGtestUnit/lit.site.cfg.py.in b/flang-rt/test/NonGtestUnit/lit.site.cfg.py.in
diff --git a/flang-rt/test/Unit/lit.cfg.py b/flang-rt/test/Unit/lit.cfg.py
diff --git a/flang-rt/test/Unit/lit.site.cfg.py.in b/flang-rt/test/Unit/lit.site.cfg.py.in
diff --git a/flang-rt/test/lit.cfg.py b/flang-rt/test/lit.cfg.py
diff --git a/flang-rt/test/lit.site.cfg.py.in b/flang-rt/test/lit.site.cfg.py.in
diff --git a/flang-rt/unittests/CMakeLists.txt b/flang-rt/unittests/CMakeLists.txt
diff --git a/flang-rt/unittests/FortranEvaluate/CMakeLists.txt b/flang-rt/unittests/FortranEvaluate/CMakeLists.txt
diff --git a/flang-rt/unittests/FortranEvaluate/testing.cpp b/flang-rt/unittests/FortranEvaluate/testing.cpp
diff --git a/flang-rt/unittests/FortranEvaluate/testing.h b/flang-rt/unittests/FortranEvaluate/testing.h
diff --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
@@ -188,7 +188,7 @@ if (FLANG_STANDALONE_BUILD)
   if (FLANG_GTEST_AVAIL)
     add_custom_target(check-all DEPENDS check-flang FlangUnitTests)
   else()
-    add_custom_target(check-all DEPENDS check-flang)
+    add_custom_target(check-all DEPENDS check-flang )
   endif()
   if (LLVM_BUILD_DOCS)
     add_custom_target(doxygen ALL)
@@ -421,11 +421,6 @@ if (FLANG_INCLUDE_TESTS)
   add_compile_definitions(FLANG_INCLUDE_TESTS=1)
 endif()
 
-# Add Flang subdirectories.
-# NOTE: The runtime subdirectory is no longer added here.
-# Sources for the runtime are added in Flang-rt.
-# TODO: Move the runtime sources to the flang-rt top level directory.
-
 add_subdirectory(include)
 add_subdirectory(lib)
 add_subdirectory(cmake/modules)
@@ -435,6 +430,7 @@ option(FLANG_BUILD_TOOLS
 if (FLANG_BUILD_TOOLS)
   add_subdirectory(tools)
 endif()
+add_subdirectory(runtime)
 
 if (LLVM_INCLUDE_EXAMPLES)
   add_subdirectory(examples)

diff --git a/flang/cmake/modules/AddFlang.cmake b/flang/cmake/modules/AddFlang.cmake
@@ -17,7 +17,7 @@ macro(add_flang_subdirectory name)
 endmacro()
 
 function(add_flang_library name)
-  set(options SHARED STATIC INSTALL_WITH_TOOLCHAIN PIC)
+  set(options SHARED STATIC INSTALL_WITH_TOOLCHAIN)
   set(multiValueArgs ADDITIONAL_HEADERS CLANG_LIBS)
   cmake_parse_arguments(ARG
     "${options}"
@@ -65,9 +65,6 @@ function(add_flang_library name)
   endif()
 
   llvm_add_library(${name} ${LIBTYPE} ${ARG_UNPARSED_ARGUMENTS} ${srcs})
-  if (ARG_PIC)
-    set_target_properties(${name} PROPERTIES POSITION_INDEPENDENT_CODE ON)
-  endif()
 
   clang_target_link_libraries(${name} PRIVATE ${ARG_CLANG_LIBS})
 

diff --git a/flang/cmake/modules/FlangConfig.cmake.in b/flang/cmake/modules/FlangConfig.cmake.in
@@ -9,8 +9,6 @@ find_package(LLVM ${LLVM_VERSION} EXACT REQUIRED CONFIG
 set(FLANG_EXPORTED_TARGETS "@FLANG_EXPORTS@")
 set(FLANG_CMAKE_DIR "@FLANG_CONFIG_CMAKE_DIR@")
 set(FLANG_INCLUDE_DIRS "@FLANG_CONFIG_INCLUDE_DIRS@")
-set(FLANG_SOURCE_DIR "@FLANG_SOURCE_DIR@")
-set(FLANG_BINARY_DIR "@FLANG_BINARY_DIR@")
 
 # Provide all our library targets to users.
 @FLANG_CONFIG_INCLUDE_EXPORTS@
diff --git a/flang/lib/Decimal/CMakeLists.txt b/flang/lib/Decimal/CMakeLists.txt
@@ -49,19 +49,7 @@ endif()
 # avoid an unwanted dependency on libstdc++.so.
 add_definitions(-U_GLIBCXX_ASSERTIONS)
 
-# Build FortranDecimal when the build target is Flang or LLVM.
-if (CMAKE_SOURCE_DIR STREQUAL FLANG_SOURCE_DIR OR CMAKE_SOURCE_DIR STREQUAL LLVM_MAIN_SRC_DIR)
-  add_flang_library(FortranDecimal
-    binary-to-decimal.cpp
-    decimal-to-binary.cpp
-  )
-# Build FortranDecimalRT for FlangRT when the build target is Runtimes.
-# Standalone builds of FlangRT is not supported.
-elseif (CMAKE_SOURCE_DIR STREQUAL Runtimes_SOURCE_DIR)
-  add_flang_library(FortranDecimalRT STATIC INSTALL_WITH_TOOLCHAIN PIC
-    binary-to-decimal.cpp
-    decimal-to-binary.cpp
-  )
-else()
-  message(FATAL_ERROR "CMAKE_SOURCE_DIR of target points to neither Flang or Flang-rt, no library added for FortranDecimal.")
-endif()
+add_flang_library(FortranDecimal INSTALL_WITH_TOOLCHAIN
+  binary-to-decimal.cpp
+  decimal-to-binary.cpp
+)
diff --git a/flang/runtime/CMakeLists.txt b/flang/runtime/CMakeLists.txt
@@ -6,14 +6,10 @@
 #
 #===------------------------------------------------------------------------===#
 
-# TODO: Maybe this file should still be added by flang/CMakeLists.txt and
-# when FLANG_STANDALONE_BUILD=On and a new variable FLANG_BUILD_RUNTIME=On
-# we should invoke an ExternalProject_Add(flang-rt ...) from here?
-
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   cmake_minimum_required(VERSION 3.20.0)
 
-  project(FortranRuntime C CXX)
+  project(FlangRuntime C CXX)
 
   set(CMAKE_CXX_STANDARD 17)
   set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
@@ -86,6 +82,8 @@ append(${NO_LTO_FLAGS} CMAKE_CXX_FLAGS)
 add_definitions(-U_GLIBCXX_ASSERTIONS)
 add_definitions(-U_LIBCPP_ENABLE_ASSERTIONS)
 
+add_subdirectory(FortranMain)
+
 set(sources
   ISO_Fortran_binding.cpp
   allocatable.cpp
@@ -270,13 +268,10 @@ if (NOT FLANG_EXPERIMENTAL_OMP_OFFLOAD_BUILD STREQUAL "off")
   endif()
 endif()
 
-add_compile_options(-fPIC)
-
-add_flang_library(FortranRuntime STATIC
+add_flang_library(FortranRuntime
   ${sources}
   LINK_LIBS
-  FortranDecimalRT
+  FortranDecimal
 
   INSTALL_WITH_TOOLCHAIN
-  PIC
 )
diff --git a/flang/runtime/sum.cpp b/flang/runtime/sum.cpp
@@ -138,15 +138,10 @@ CppTypeFor<TypeCategory::Real, 10> RTNAME(SumReal10)(const Descriptor &x,
 }
 #endif
 #if LDBL_MANT_DIG == 113 || HAS_FLOAT128
-#if HAS_FLOAT128
-using AccumType = __float128;
-#else // if LDBL_MANT_DIG == 113
-using AccumType = long double;
-#endif
 CppTypeFor<TypeCategory::Real, 16> RTNAME(SumReal16)(const Descriptor &x,
     const char *source, int line, int dim, const Descriptor *mask) {
   return GetTotalReduction<TypeCategory::Real, 16>(
-      x, source, line, dim, mask, RealSumAccumulator<AccumType>{x}, "SUM");
+      x, source, line, dim, mask, RealSumAccumulator<long double>{x}, "SUM");
 }
 #endif
 

diff --git a/flang/test/CMakeLists.txt b/flang/test/CMakeLists.txt
@@ -61,6 +61,9 @@ set(FLANG_TEST_DEPENDS
   llvm-objdump
   llvm-readobj
   split-file
+  FortranRuntime
+  Fortran_main
+  FortranDecimal
 )
 if (LLVM_ENABLE_PLUGINS AND NOT WIN32)
   list(APPEND FLANG_TEST_DEPENDS Bye)

diff --git a/flang/test/Driver/linker-flags.f90 b/flang/test/Driver/linker-flags.f90
@@ -24,25 +24,29 @@
 ! GNU-LABEL:  "{{.*}}ld{{(\.exe)?}}"
 ! GNU-SAME: "[[object_file]]"
 ! GNU-SAME: -lFortran_main
-! GNU-SAME: -lflang-rt
+! GNU-SAME: -lFortranRuntime
+! GNU-SAME: -lFortranDecimal
 ! GNU-SAME: -lm
 
 ! DARWIN-LABEL:  "{{.*}}ld{{(\.exe)?}}"
 ! DARWIN-SAME: "[[object_file]]"
 ! DARWIN-SAME: -lFortran_main
-! DARWIN-SAME: -lflang-rt
+! DARWIN-SAME: -lFortranRuntime
+! DARWIN-SAME: -lFortranDecimal
 
 ! MINGW-LABEL:  "{{.*}}ld{{(\.exe)?}}"
 ! MINGW-SAME: "[[object_file]]"
 ! MINGW-SAME: -lFortran_main
-! MINGW-SAME: -lflang-rt
+! MINGW-SAME: -lFortranRuntime
+! MINGW-SAME: -lFortranDecimal
 
 ! NOTE: This also matches lld-link (when CLANG_DEFAULT_LINKER=lld) and
 !       any .exe suffix that is added when resolving to the full path of
 !       (lld-)link.exe on Windows platforms. The suffix may not be added
 !       when the executable is not found or on non-Windows platforms.
 ! MSVC-LABEL: link
 ! MSVC-SAME: Fortran_main.lib
-! MSVC-SAME: flang-rt.lib
+! MSVC-SAME: FortranRuntime.lib
+! MSVC-SAME: FortranDecimal.lib
 ! MSVC-SAME: /subsystem:console
 ! MSVC-SAME: "[[object_file]]"
diff --git a/flang/test/lit.cfg.py b/flang/test/lit.cfg.py
@@ -153,16 +153,19 @@
 # the C++ runtime libraries. For this we need a C compiler. If for some reason
 # we don't have one, we can just disable the test.
 if config.cc:
-    libruntime = os.path.join(config.flang_lib_dir, "libflang-rt.a")
+    libruntime = os.path.join(config.flang_lib_dir, "libFortranRuntime.a")
+    libdecimal = os.path.join(config.flang_lib_dir, "libFortranDecimal.a")
     include = os.path.join(config.flang_src_dir, "include")
 
     if (
         os.path.isfile(libruntime)
+        and os.path.isfile(libdecimal)
         and os.path.isdir(include)
     ):
         config.available_features.add("c-compiler")
         tools.append(ToolSubst("%cc", command=config.cc, unresolved="fatal"))
         tools.append(ToolSubst("%libruntime", command=libruntime, unresolved="fatal"))
+        tools.append(ToolSubst("%libdecimal", command=libdecimal, unresolved="fatal"))
         tools.append(ToolSubst("%include", command=include, unresolved="fatal"))
 
 # Add all the tools and their substitutions (if applicable). Use the search paths provided for

diff --git a/flang/tools/flang-driver/CMakeLists.txt b/flang/tools/flang-driver/CMakeLists.txt
@@ -14,6 +14,14 @@ set( LLVM_LINK_COMPONENTS
 add_flang_tool(flang-new
   driver.cpp
   fc1_main.cpp
+
+  DEPENDS
+  # These libraries are used in the linker invocation generated by the driver
+  # (i.e. when constructing the linker job). Without them the driver would be
+  # unable to generate executables.
+  FortranRuntime
+  FortranDecimal
+  Fortran_main
 )
 
 target_link_libraries(flang-new

diff --git a/flang/unittests/CMakeLists.txt b/flang/unittests/CMakeLists.txt
@@ -24,15 +24,11 @@ function(add_flang_unittest_offload_properties target)
   # FIXME: replace 'native' in --offload-arch option with the list
   #        of targets that Fortran Runtime was built for.
   #        Common code must be moved from flang/runtime/CMakeLists.txt.
-  # TODO: Revisit this because of Flang-rt. runtime is no longer an added subdirectory of flang. So we temporarily duplicated the option definition to here. This is not a permanent solution.
-  set(FLANG_EXPERIMENTAL_OMP_OFFLOAD_BUILD "off" CACHE STRING
-    "Compile Fortran runtime as OpenMP target offload sources (experimental). Valid options are 'off', 'host_device', 'nohost'")
-
   if (NOT FLANG_EXPERIMENTAL_OMP_OFFLOAD_BUILD STREQUAL "off")
     set_target_properties(${target}
-        PROPERTIES LINK_OPTIONS
-        "-fopenmp;--offload-arch=native"
-    )
+      PROPERTIES LINK_OPTIONS
+      "-fopenmp;--offload-arch=native"
+      )
   endif()
 endfunction()
 
@@ -78,4 +74,5 @@ add_subdirectory(Optimizer)
 add_subdirectory(Common)
 add_subdirectory(Decimal)
 add_subdirectory(Evaluate)
+add_subdirectory(Runtime)
 add_subdirectory(Frontend)
diff --git a/flang/unittests/Evaluate/CMakeLists.txt b/flang/unittests/Evaluate/CMakeLists.txt
@@ -45,6 +45,7 @@ add_flang_nongtest_unittest(intrinsics
   FortranDecimal
   FortranSemantics
   FortranParser
+  FortranRuntime
 )
 
 add_flang_nongtest_unittest(logical
@@ -67,6 +68,20 @@ add_flang_nongtest_unittest(real
 )
 llvm_update_compile_flags(real.test)
 
+add_flang_nongtest_unittest(reshape
+  FortranEvaluateTesting
+  FortranSemantics
+  FortranEvaluate
+  FortranRuntime
+)
+
+add_flang_nongtest_unittest(ISO-Fortran-binding
+  FortranEvaluateTesting
+  FortranEvaluate
+  FortranSemantics
+  FortranRuntime
+)
+
 add_flang_nongtest_unittest(folding
   FortranCommon
   FortranEvaluateTesting

diff --git a/...s/FortranEvaluate/ISO-Fortran-binding.cpp → ...nittests/Evaluate/ISO-Fortran-binding.cpp b/...s/FortranEvaluate/ISO-Fortran-binding.cpp → ...nittests/Evaluate/ISO-Fortran-binding.cpp
diff --git a/...-rt/unittests/FortranEvaluate/reshape.cpp → flang/unittests/Evaluate/reshape.cpp b/...-rt/unittests/FortranEvaluate/reshape.cpp → flang/unittests/Evaluate/reshape.cpp
diff --git a/flang/unittests/Optimizer/CMakeLists.txt b/flang/unittests/Optimizer/CMakeLists.txt
@@ -19,6 +19,16 @@ add_flang_unittest(FlangOptimizerTests
   Builder/DoLoopHelperTest.cpp
   Builder/FIRBuilderTest.cpp
   Builder/HLFIRToolsTest.cpp
+  Builder/Runtime/AllocatableTest.cpp
+  Builder/Runtime/AssignTest.cpp
+  Builder/Runtime/CommandTest.cpp
+  Builder/Runtime/CharacterTest.cpp
+  Builder/Runtime/DerivedTest.cpp
+  Builder/Runtime/NumericTest.cpp
+  Builder/Runtime/RaggedTest.cpp
+  Builder/Runtime/ReductionTest.cpp
+  Builder/Runtime/StopTest.cpp
+  Builder/Runtime/TransformationalTest.cpp
   FIRContextTest.cpp
   FIRTypesTest.cpp
   FortranVariableTest.cpp

diff --git a/.../unittests/FortranRuntime/Allocatable.cpp → flang/unittests/Runtime/Allocatable.cpp b/.../unittests/FortranRuntime/Allocatable.cpp → flang/unittests/Runtime/Allocatable.cpp
diff --git a/...tests/FortranRuntime/ArrayConstructor.cpp → flang/unittests/Runtime/ArrayConstructor.cpp b/...tests/FortranRuntime/ArrayConstructor.cpp → flang/unittests/Runtime/ArrayConstructor.cpp
diff --git a/...t/unittests/FortranRuntime/BufferTest.cpp → flang/unittests/Runtime/BufferTest.cpp b/...t/unittests/FortranRuntime/BufferTest.cpp → flang/unittests/Runtime/BufferTest.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang/../../runtime/buffer.h"
+#include "../../runtime/buffer.h"
 #include "CrashHandlerFixture.h"
 #include "gtest/gtest.h"
 #include <algorithm>
@@ -30,31 +30,30 @@ class Store : public FileFrame<Store, tinyBufferSize> {
   void set_expect(FileOffset to) { expect_ = to; }
 
   std::size_t Read(FileOffset at, char *to, std::size_t minBytes,
-                   std::size_t maxBytes, IoErrorHandler &handler) {
+      std::size_t maxBytes, IoErrorHandler &handler) {
     if (enforceSequence_ && at != expect_) {
       handler.SignalError("Read(%d,%d,%d) not at expected %d",
-                          static_cast<int>(at), static_cast<int>(minBytes),
-                          static_cast<int>(maxBytes),
-                          static_cast<int>(expect_));
+          static_cast<int>(at), static_cast<int>(minBytes),
+          static_cast<int>(maxBytes), static_cast<int>(expect_));
     } else if (at < 0 || at + minBytes > bytes_) {
       handler.SignalError("Read(%d,%d,%d) is out of bounds",
-                          static_cast<int>(at), static_cast<int>(minBytes),
-                          static_cast<int>(maxBytes));
+          static_cast<int>(at), static_cast<int>(minBytes),
+          static_cast<int>(maxBytes));
     }
     auto result{std::min<std::size_t>(maxBytes, bytes_ - at)};
     std::memcpy(to, &data_[at], result);
     expect_ = at + result;
     return result;
   }
   std::size_t Write(FileOffset at, const char *from, std::size_t bytes,
-                    IoErrorHandler &handler) {
+      IoErrorHandler &handler) {
     if (enforceSequence_ && at != expect_) {
       handler.SignalError("Write(%d,%d) not at expected %d",
-                          static_cast<int>(at), static_cast<int>(bytes),
-                          static_cast<int>(expect_));
+          static_cast<int>(at), static_cast<int>(bytes),
+          static_cast<int>(expect_));
     } else if (at < 0 || at + bytes > bytes_) {
       handler.SignalError("Write(%d,%d) is out of bounds", static_cast<int>(at),
-                          static_cast<int>(bytes));
+          static_cast<int>(bytes));
     }
     std::memcpy(&data_[at], from, bytes);
     expect_ = at + bytes;
@@ -71,8 +70,8 @@ class Store : public FileFrame<Store, tinyBufferSize> {
 inline int ChunkSize(int j, int most) {
   // 31, 1, 29, 3, 27, ...
   j %= tinyBufferSize;
-  auto chunk{static_cast<int>(((j % 2) ? j : (tinyBufferSize - 1 - j)) %
-                              tinyBufferSize)};
+  auto chunk{static_cast<int>(
+      ((j % 2) ? j : (tinyBufferSize - 1 - j)) % tinyBufferSize)};
   return std::min(chunk, most);
 }
 

diff --git a/...t/unittests/FortranRuntime/CMakeLists.txt → flang/unittests/Runtime/CMakeLists.txt b/...t/unittests/FortranRuntime/CMakeLists.txt → flang/unittests/Runtime/CMakeLists.txt
@@ -1,4 +1,4 @@
-add_flang_rt_unittest(FortranRuntimeTests
+add_flang_unittest(FlangRuntimeTests
   Allocatable.cpp
   ArrayConstructor.cpp
   BufferTest.cpp
@@ -29,7 +29,7 @@ add_flang_rt_unittest(FortranRuntimeTests
   Transformational.cpp
 )
 
-target_link_libraries(FortranRuntimeTests
+target_link_libraries(FlangRuntimeTests
   PRIVATE
-  flang-rt
+  FortranRuntime
 )
diff --git a/...nittests/FortranRuntime/CharacterTest.cpp → flang/unittests/Runtime/CharacterTest.cpp b/...nittests/FortranRuntime/CharacterTest.cpp → flang/unittests/Runtime/CharacterTest.cpp
diff --git a/.../unittests/FortranRuntime/CommandTest.cpp → flang/unittests/Runtime/CommandTest.cpp b/.../unittests/FortranRuntime/CommandTest.cpp → flang/unittests/Runtime/CommandTest.cpp
diff --git a/...g-rt/unittests/FortranRuntime/Complex.cpp → flang/unittests/Runtime/Complex.cpp b/...g-rt/unittests/FortranRuntime/Complex.cpp → flang/unittests/Runtime/Complex.cpp
diff --git a/...ts/FortranRuntime/CrashHandlerFixture.cpp → ...unittests/Runtime/CrashHandlerFixture.cpp b/...ts/FortranRuntime/CrashHandlerFixture.cpp → ...unittests/Runtime/CrashHandlerFixture.cpp
@@ -6,13 +6,13 @@
 //
 //===----------------------------------------------------------------------===//
 #include "CrashHandlerFixture.h"
-#include "flang/../../runtime/terminator.h"
+#include "../../runtime/terminator.h"
 #include <cstdarg>
 #include <cstdlib>
 
 // Replaces Fortran runtime's crash handler so we can verify the crash message
-[[noreturn]] static void CatchCrash(const char *sourceFile, int sourceLine,
-                                    const char *message, va_list &ap) {
+[[noreturn]] static void CatchCrash(
+    const char *sourceFile, int sourceLine, const char *message, va_list &ap) {
   char buffer[1000];
   std::vsnprintf(buffer, sizeof buffer, message, ap);
   va_end(ap);

diff --git a/...ests/FortranRuntime/CrashHandlerFixture.h → ...g/unittests/Runtime/CrashHandlerFixture.h b/...ests/FortranRuntime/CrashHandlerFixture.h → ...g/unittests/Runtime/CrashHandlerFixture.h
diff --git a/...g-rt/unittests/FortranRuntime/Derived.cpp → flang/unittests/Runtime/Derived.cpp b/...g-rt/unittests/FortranRuntime/Derived.cpp → flang/unittests/Runtime/Derived.cpp
diff --git a/...ittests/FortranRuntime/ExternalIOTest.cpp → flang/unittests/Runtime/ExternalIOTest.cpp b/...ittests/FortranRuntime/ExternalIOTest.cpp → flang/unittests/Runtime/ExternalIOTest.cpp
diff --git a/flang-rt/unittests/FortranRuntime/Format.cpp → flang/unittests/Runtime/Format.cpp b/flang-rt/unittests/FortranRuntime/Format.cpp → flang/unittests/Runtime/Format.cpp
diff --git a/...g-rt/unittests/FortranRuntime/Inquiry.cpp → flang/unittests/Runtime/Inquiry.cpp b/...g-rt/unittests/FortranRuntime/Inquiry.cpp → flang/unittests/Runtime/Inquiry.cpp
diff --git a/...nittests/FortranRuntime/ListInputTest.cpp → flang/unittests/Runtime/ListInputTest.cpp b/...nittests/FortranRuntime/ListInputTest.cpp → flang/unittests/Runtime/ListInputTest.cpp
@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "CrashHandlerFixture.h"
-#include "flang/../../runtime/io-error.h"
+#include "../../runtime/io-error.h"
 #include "flang/Runtime/descriptor.h"
 #include "flang/Runtime/io-api.h"
 
@@ -36,15 +36,15 @@ TEST(InputTest, TestListInputAlphabet) {
   // Use _two_ input buffers and _three_ output buffers. Note the `3*` in the
   // _inputBuffers_.
   SetCharacter(inputBuffers[j++], maxInputBufferLength,
-               "3*'abcdefghijklmnopqrstuvwxyzABC");
-  SetCharacter(inputBuffers[j++], maxInputBufferLength,
-               "DEFGHIJKLMNOPQRSTUVWXYZ'");
+      "3*'abcdefghijklmnopqrstuvwxyzABC");
+  SetCharacter(
+      inputBuffers[j++], maxInputBufferLength, "DEFGHIJKLMNOPQRSTUVWXYZ'");
 
   StaticDescriptor<1> staticDescriptor;
   Descriptor &whole{staticDescriptor.descriptor()};
   SubscriptValue extent[]{numInputBuffers};
   whole.Establish(TypeCode{CFI_type_char}, maxInputBufferLength, &inputBuffers,
-                  1, extent, CFI_attribute_pointer);
+      1, extent, CFI_attribute_pointer);
   whole.Check();
   auto *cookie{IONAME(BeginInternalArrayListInput)(whole)};
 
@@ -79,7 +79,7 @@ TEST(InputTest, TestListInputIntegerList) {
   Descriptor &whole{staticDescriptor.descriptor()};
   SubscriptValue extent[]{numBuffers};
   whole.Establish(TypeCode{CFI_type_char}, maxBufferLength, &buffer, 1, extent,
-                  CFI_attribute_pointer);
+      CFI_attribute_pointer);
   whole.Check();
   auto *cookie{IONAME(BeginInternalArrayListInput)(whole)};
 
@@ -88,10 +88,10 @@ TEST(InputTest, TestListInputIntegerList) {
   // Negative numbers will be overwritten by _expectedOutput_, and positive
   // numbers will not be as their indices are "Null values" of the Fortran 2018
   // standard 13.10.3.2 in the format strings _buffer_
-  std::int64_t actualOutput[listInputLength]{-1, -2, -3, -4, 5,
-                                             -6, 7,  -8, 9,  10};
-  const std::int64_t expectedOutput[listInputLength]{1, 2, 3, 3, 5,
-                                                     6, 7, 8, 9, 10};
+  std::int64_t actualOutput[listInputLength]{
+      -1, -2, -3, -4, 5, -6, 7, -8, 9, 10};
+  const std::int64_t expectedOutput[listInputLength]{
+      1, 2, 3, 3, 5, 6, 7, 8, 9, 10};
   for (j = 0; j < listInputLength; ++j) {
     IONAME(InputInteger)(cookie, actualOutput[j]);
   }
@@ -116,7 +116,7 @@ TEST(InputTest, TestListInputInvalidFormatWithSingleSuccess) {
   Descriptor &whole{staticDescriptor.descriptor()};
   SubscriptValue extent[]{numBuffers};
   whole.Establish(TypeCode{CFI_type_char}, formatBuffer.size(),
-                  formatBuffer.data(), 1, extent, CFI_attribute_pointer);
+      formatBuffer.data(), 1, extent, CFI_attribute_pointer);
   whole.Check();
 
   auto *cookie{IONAME(BeginInternalArrayListInput)(whole)};
@@ -127,7 +127,7 @@ TEST(InputTest, TestListInputInvalidFormatWithSingleSuccess) {
 
   // Perform failing InputInteger
   ASSERT_DEATH(IONAME(InputInteger)(cookie, dummy),
-               "Bad character 'g' in INTEGER input field");
+      "Bad character 'g' in INTEGER input field");
 }
 
 // Same test as _TestListInputInvalidFormatWithSingleSuccess_, however no
@@ -140,15 +140,15 @@ TEST(InputTest, TestListInputInvalidFormat) {
   Descriptor &whole{staticDescriptor.descriptor()};
   SubscriptValue extent[]{numBuffers};
   whole.Establish(TypeCode{CFI_type_char}, formatBuffer.size(),
-                  formatBuffer.data(), 1, extent, CFI_attribute_pointer);
+      formatBuffer.data(), 1, extent, CFI_attribute_pointer);
   whole.Check();
 
   auto *cookie{IONAME(BeginInternalArrayListInput)(whole)};
   std::int64_t dummy;
 
   // Perform failing InputInteger
   ASSERT_DEATH(IONAME(InputInteger)(cookie, dummy),
-               "Bad character 'g' in INTEGER input field");
+      "Bad character 'g' in INTEGER input field");
 }
 
 using ParamTy = std::tuple<std::string, std::vector<int>>;
@@ -163,7 +163,7 @@ TEST_P(SimpleListInputTest, TestListInput) {
   Descriptor &whole{staticDescriptor.descriptor()};
   SubscriptValue extent[]{numBuffers};
   whole.Establish(TypeCode{CFI_type_char}, formatBuffer.size(),
-                  formatBuffer.data(), 1, extent, CFI_attribute_pointer);
+      formatBuffer.data(), 1, extent, CFI_attribute_pointer);
   whole.Check();
   auto *cookie{IONAME(BeginInternalArrayListInput)(whole)};
 
@@ -185,10 +185,9 @@ TEST_P(SimpleListInputTest, TestListInput) {
   }
 }
 
-INSTANTIATE_TEST_SUITE_P(
-    SimpleListInputTestInstantiation, SimpleListInputTest,
+INSTANTIATE_TEST_SUITE_P(SimpleListInputTestInstantiation, SimpleListInputTest,
     testing::Values(std::make_tuple("", std::vector<int>{}),
-                    std::make_tuple("0", std::vector<int>{}),
-                    std::make_tuple("1", std::vector<int>{1}),
-                    std::make_tuple("1, 2", std::vector<int>{1, 2}),
-                    std::make_tuple("3*2", std::vector<int>{2, 2, 2})));
+        std::make_tuple("0", std::vector<int>{}),
+        std::make_tuple("1", std::vector<int>{1}),
+        std::make_tuple("1, 2", std::vector<int>{1, 2}),
+        std::make_tuple("3*2", std::vector<int>{2, 2, 2})));
diff --git a/...ests/FortranRuntime/LogicalFormatTest.cpp → ...g/unittests/Runtime/LogicalFormatTest.cpp b/...ests/FortranRuntime/LogicalFormatTest.cpp → ...g/unittests/Runtime/LogicalFormatTest.cpp
diff --git a/flang-rt/unittests/FortranRuntime/Matmul.cpp → flang/unittests/Runtime/Matmul.cpp b/flang-rt/unittests/FortranRuntime/Matmul.cpp → flang/unittests/Runtime/Matmul.cpp
diff --git a/...ttests/FortranRuntime/MatmulTranspose.cpp → flang/unittests/Runtime/MatmulTranspose.cpp b/...ttests/FortranRuntime/MatmulTranspose.cpp → flang/unittests/Runtime/MatmulTranspose.cpp
diff --git a/...nittests/FortranRuntime/MiscIntrinsic.cpp → flang/unittests/Runtime/MiscIntrinsic.cpp b/...nittests/FortranRuntime/MiscIntrinsic.cpp → flang/unittests/Runtime/MiscIntrinsic.cpp
diff --git a/...-rt/unittests/FortranRuntime/Namelist.cpp → flang/unittests/Runtime/Namelist.cpp b/...-rt/unittests/FortranRuntime/Namelist.cpp → flang/unittests/Runtime/Namelist.cpp
@@ -6,11 +6,11 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang/../../runtime/namelist.h"
+#include "../../runtime/namelist.h"
 #include "CrashHandlerFixture.h"
+#include "tools.h"
 #include "flang/Runtime/descriptor.h"
 #include "flang/Runtime/io-api.h"
-#include "tools.h"
 #include <algorithm>
 #include <cinttypes>
 #include <complex>
@@ -27,7 +27,7 @@ struct NamelistTests : CrashHandlerFixture {};
 
 static void ClearDescriptorStorage(const Descriptor &descriptor) {
   std::memset(descriptor.raw().base_addr, 0,
-              descriptor.Elements() * descriptor.ElementBytes());
+      descriptor.Elements() * descriptor.ElementBytes());
 }
 
 TEST(NamelistTests, BasicSanity) {
@@ -38,20 +38,17 @@ TEST(NamelistTests, BasicSanity) {
   Descriptor &internalDesc{statDescs[0].descriptor()};
   SubscriptValue extent[]{numLines};
   internalDesc.Establish(TypeCode{CFI_type_char}, /*elementBytes=*/lineLength,
-                         &buffer, 1, extent, CFI_attribute_pointer);
+      &buffer, 1, extent, CFI_attribute_pointer);
   // Set up data arrays
   std::vector<int> ints;
   for (int j{0}; j < 20; ++j) {
     ints.push_back(j % 2 == 0 ? (1 << j) : -(1 << j));
   }
-  std::vector<double> reals{0.0,
-                            -0.0,
-                            std::numeric_limits<double>::infinity(),
-                            -std::numeric_limits<double>::infinity(),
-                            std::numeric_limits<double>::quiet_NaN(),
-                            std::numeric_limits<double>::max(),
-                            std::numeric_limits<double>::lowest(),
-                            std::numeric_limits<double>::epsilon()};
+  std::vector<double> reals{0.0, -0.0, std::numeric_limits<double>::infinity(),
+      -std::numeric_limits<double>::infinity(),
+      std::numeric_limits<double>::quiet_NaN(),
+      std::numeric_limits<double>::max(), std::numeric_limits<double>::lowest(),
+      std::numeric_limits<double>::epsilon()};
   std::vector<std::uint8_t> logicals;
   logicals.push_back(false);
   logicals.push_back(true);
@@ -79,14 +76,12 @@ TEST(NamelistTests, BasicSanity) {
   // Create a NAMELIST group
   static constexpr int items{5};
   const NamelistGroup::Item itemArray[items]{{"ints", *intDesc},
-                                             {"reals", *realDesc},
-                                             {"logicals", *logicalDesc},
-                                             {"complexes", *complexDesc},
-                                             {"characters", *characterDesc}};
+      {"reals", *realDesc}, {"logicals", *logicalDesc},
+      {"complexes", *complexDesc}, {"characters", *characterDesc}};
   const NamelistGroup group{"group1", items, itemArray};
   // Do an internal NAMELIST write and check results
-  auto outCookie1{IONAME(BeginInternalArrayListOutput)(internalDesc, nullptr, 0,
-                                                       __FILE__, __LINE__)};
+  auto outCookie1{IONAME(BeginInternalArrayListOutput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(SetDelim)(outCookie1, "APOSTROPHE", 10));
   ASSERT_TRUE(IONAME(OutputNamelist)(outCookie1, group));
   auto outStatus1{IONAME(EndIoStatement)(outCookie1)};
@@ -114,14 +109,14 @@ TEST(NamelistTests, BasicSanity) {
   ClearDescriptorStorage(*logicalDesc);
   ClearDescriptorStorage(*complexDesc);
   ClearDescriptorStorage(*characterDesc);
-  auto inCookie{IONAME(BeginInternalArrayListInput)(internalDesc, nullptr, 0,
-                                                    __FILE__, __LINE__)};
+  auto inCookie{IONAME(BeginInternalArrayListInput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(InputNamelist)(inCookie, group));
   auto inStatus{IONAME(EndIoStatement)(inCookie)};
   ASSERT_EQ(inStatus, 0) << "Failed namelist input sanity, status "
                          << static_cast<int>(inStatus);
-  auto outCookie2{IONAME(BeginInternalArrayListOutput)(internalDesc, nullptr, 0,
-                                                       __FILE__, __LINE__)};
+  auto outCookie2{IONAME(BeginInternalArrayListOutput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(SetDelim)(outCookie2, "APOSTROPHE", 10));
   ASSERT_TRUE(IONAME(OutputNamelist)(outCookie2, group));
   auto outStatus2{IONAME(EndIoStatement)(outCookie2)};
@@ -144,19 +139,18 @@ TEST(NamelistTests, Subscripts) {
   StaticDescriptor<1, true> statDesc;
   Descriptor &internalDesc{statDesc.descriptor()};
   internalDesc.Establish(TypeCode{CFI_type_char},
-                         /*elementBytes=*/std::strlen(t1), t1, 0, nullptr,
-                         CFI_attribute_pointer);
-  auto inCookie{IONAME(BeginInternalArrayListInput)(internalDesc, nullptr, 0,
-                                                    __FILE__, __LINE__)};
+      /*elementBytes=*/std::strlen(t1), t1, 0, nullptr, CFI_attribute_pointer);
+  auto inCookie{IONAME(BeginInternalArrayListInput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(InputNamelist)(inCookie, group));
   auto inStatus{IONAME(EndIoStatement)(inCookie)};
   ASSERT_EQ(inStatus, 0) << "Failed namelist input subscripts, status "
                          << static_cast<int>(inStatus);
   char out[40];
   internalDesc.Establish(TypeCode{CFI_type_char}, /*elementBytes=*/sizeof out,
-                         out, 0, nullptr, CFI_attribute_pointer);
-  auto outCookie{IONAME(BeginInternalArrayListOutput)(internalDesc, nullptr, 0,
-                                                      __FILE__, __LINE__)};
+      out, 0, nullptr, CFI_attribute_pointer);
+  auto outCookie{IONAME(BeginInternalArrayListOutput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(OutputNamelist)(outCookie, group));
   auto outStatus{IONAME(EndIoStatement)(outCookie)};
   ASSERT_EQ(outStatus, 0)
@@ -183,8 +177,8 @@ TEST(NamelistTests, ShortArrayInput) {
   Descriptor &internalDesc{statDesc.descriptor()};
   SubscriptValue shape{2};
   internalDesc.Establish(1, 12, t1, 1, &shape, CFI_attribute_pointer);
-  auto inCookie{IONAME(BeginInternalArrayListInput)(internalDesc, nullptr, 0,
-                                                    __FILE__, __LINE__)};
+  auto inCookie{IONAME(BeginInternalArrayListInput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(InputNamelist)(inCookie, group));
   auto inStatus{IONAME(EndIoStatement)(inCookie)};
   ASSERT_EQ(inStatus, 0) << "Failed namelist input subscripts, status "
@@ -204,18 +198,17 @@ TEST(NamelistTests, ScalarSubstring) {
   StaticDescriptor<1, true> statDesc;
   Descriptor &internalDesc{statDesc.descriptor()};
   internalDesc.Establish(TypeCode{CFI_type_char},
-                         /*elementBytes=*/std::strlen(t1), t1, 0, nullptr,
-                         CFI_attribute_pointer);
-  auto inCookie{IONAME(BeginInternalArrayListInput)(internalDesc, nullptr, 0,
-                                                    __FILE__, __LINE__)};
+      /*elementBytes=*/std::strlen(t1), t1, 0, nullptr, CFI_attribute_pointer);
+  auto inCookie{IONAME(BeginInternalArrayListInput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(InputNamelist)(inCookie, group));
   ASSERT_EQ(IONAME(EndIoStatement)(inCookie), IostatOk)
       << "namelist scalar substring input";
   char out[32];
   internalDesc.Establish(TypeCode{CFI_type_char}, /*elementBytes=*/sizeof out,
-                         out, 0, nullptr, CFI_attribute_pointer);
-  auto outCookie{IONAME(BeginInternalArrayListOutput)(internalDesc, nullptr, 0,
-                                                      __FILE__, __LINE__)};
+      out, 0, nullptr, CFI_attribute_pointer);
+  auto outCookie{IONAME(BeginInternalArrayListOutput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(SetDelim)(outCookie, "apostrophe", 10));
   ASSERT_TRUE(IONAME(OutputNamelist)(outCookie, group));
   ASSERT_EQ(IONAME(EndIoStatement)(outCookie), IostatOk) << "namelist output";
@@ -225,27 +218,26 @@ TEST(NamelistTests, ScalarSubstring) {
 }
 
 TEST(NamelistTests, ArraySubstring) {
-  OwningPtr<Descriptor> scDesc{MakeArray<TypeCategory::Character, 1>(
-      std::vector<int>{2}, std::vector<std::string>{"abcdefgh", "ijklmnop"},
-      8)};
+  OwningPtr<Descriptor> scDesc{
+      MakeArray<TypeCategory::Character, 1>(std::vector<int>{2},
+          std::vector<std::string>{"abcdefgh", "ijklmnop"}, 8)};
   const NamelistGroup::Item items[]{{"a", *scDesc}};
   const NamelistGroup group{"justa", 1, items};
   static char t1[]{"&justa A(:)(2:+5)='BCDE' 'JKLM'/"};
   StaticDescriptor<1, true> statDesc;
   Descriptor &internalDesc{statDesc.descriptor()};
   internalDesc.Establish(TypeCode{CFI_type_char},
-                         /*elementBytes=*/std::strlen(t1), t1, 0, nullptr,
-                         CFI_attribute_pointer);
-  auto inCookie{IONAME(BeginInternalArrayListInput)(internalDesc, nullptr, 0,
-                                                    __FILE__, __LINE__)};
+      /*elementBytes=*/std::strlen(t1), t1, 0, nullptr, CFI_attribute_pointer);
+  auto inCookie{IONAME(BeginInternalArrayListInput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(InputNamelist)(inCookie, group));
   ASSERT_EQ(IONAME(EndIoStatement)(inCookie), IostatOk)
       << "namelist scalar substring input";
   char out[40];
   internalDesc.Establish(TypeCode{CFI_type_char}, /*elementBytes=*/sizeof out,
-                         out, 0, nullptr, CFI_attribute_pointer);
-  auto outCookie{IONAME(BeginInternalArrayListOutput)(internalDesc, nullptr, 0,
-                                                      __FILE__, __LINE__)};
+      out, 0, nullptr, CFI_attribute_pointer);
+  auto outCookie{IONAME(BeginInternalArrayListOutput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(SetDelim)(outCookie, "apostrophe", 10));
   ASSERT_TRUE(IONAME(OutputNamelist)(outCookie, group));
   ASSERT_EQ(IONAME(EndIoStatement)(outCookie), IostatOk) << "namelist output";
@@ -264,18 +256,17 @@ TEST(NamelistTests, Skip) {
   StaticDescriptor<1, true> statDesc;
   Descriptor &internalDesc{statDesc.descriptor()};
   internalDesc.Establish(TypeCode{CFI_type_char},
-                         /*elementBytes=*/std::strlen(t1), t1, 0, nullptr,
-                         CFI_attribute_pointer);
-  auto inCookie{IONAME(BeginInternalArrayListInput)(internalDesc, nullptr, 0,
-                                                    __FILE__, __LINE__)};
+      /*elementBytes=*/std::strlen(t1), t1, 0, nullptr, CFI_attribute_pointer);
+  auto inCookie{IONAME(BeginInternalArrayListInput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(InputNamelist)(inCookie, group));
   ASSERT_EQ(IONAME(EndIoStatement)(inCookie), IostatOk)
       << "namelist input with skipping";
   char out[20];
   internalDesc.Establish(TypeCode{CFI_type_char}, /*elementBytes=*/sizeof out,
-                         out, 0, nullptr, CFI_attribute_pointer);
-  auto outCookie{IONAME(BeginInternalArrayListOutput)(internalDesc, nullptr, 0,
-                                                      __FILE__, __LINE__)};
+      out, 0, nullptr, CFI_attribute_pointer);
+  auto outCookie{IONAME(BeginInternalArrayListOutput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(OutputNamelist)(outCookie, group));
   ASSERT_EQ(IONAME(EndIoStatement)(outCookie), IostatOk) << "namelist output";
   std::string got{out, sizeof out};
@@ -294,19 +285,18 @@ TEST(NamelistTests, Comma) {
   StaticDescriptor<1, true> statDesc;
   Descriptor &internalDesc{statDesc.descriptor()};
   internalDesc.Establish(TypeCode{CFI_type_char},
-                         /*elementBytes=*/std::strlen(t1), t1, 0, nullptr,
-                         CFI_attribute_pointer);
-  auto inCookie{IONAME(BeginInternalArrayListInput)(internalDesc, nullptr, 0,
-                                                    __FILE__, __LINE__)};
+      /*elementBytes=*/std::strlen(t1), t1, 0, nullptr, CFI_attribute_pointer);
+  auto inCookie{IONAME(BeginInternalArrayListInput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(SetDecimal)(inCookie, "COMMA", 5));
   ASSERT_TRUE(IONAME(InputNamelist)(inCookie, group));
   ASSERT_EQ(IONAME(EndIoStatement)(inCookie), IostatOk)
       << "namelist input with skipping";
   char out[30];
   internalDesc.Establish(TypeCode{CFI_type_char}, /*elementBytes=*/sizeof out,
-                         out, 0, nullptr, CFI_attribute_pointer);
-  auto outCookie{IONAME(BeginInternalArrayListOutput)(internalDesc, nullptr, 0,
-                                                      __FILE__, __LINE__)};
+      out, 0, nullptr, CFI_attribute_pointer);
+  auto outCookie{IONAME(BeginInternalArrayListOutput)(
+      internalDesc, nullptr, 0, __FILE__, __LINE__)};
   ASSERT_TRUE(IONAME(SetDecimal)(outCookie, "COMMA", 5));
   ASSERT_TRUE(IONAME(OutputNamelist)(outCookie, group));
   ASSERT_EQ(IONAME(EndIoStatement)(outCookie), IostatOk) << "namelist output";

diff --git a/...g-rt/unittests/FortranRuntime/Numeric.cpp → flang/unittests/Runtime/Numeric.cpp b/...g-rt/unittests/FortranRuntime/Numeric.cpp → flang/unittests/Runtime/Numeric.cpp
diff --git a/...ts/FortranRuntime/NumericalFormatTest.cpp → ...unittests/Runtime/NumericalFormatTest.cpp b/...ts/FortranRuntime/NumericalFormatTest.cpp → ...unittests/Runtime/NumericalFormatTest.cpp
diff --git a/...g-rt/unittests/FortranRuntime/Pointer.cpp → flang/unittests/Runtime/Pointer.cpp b/...g-rt/unittests/FortranRuntime/Pointer.cpp → flang/unittests/Runtime/Pointer.cpp
diff --git a/flang-rt/unittests/FortranRuntime/Ragged.cpp → flang/unittests/Runtime/Ragged.cpp b/flang-rt/unittests/FortranRuntime/Ragged.cpp → flang/unittests/Runtime/Ragged.cpp
diff --git a/flang-rt/unittests/FortranRuntime/Random.cpp → flang/unittests/Runtime/Random.cpp b/flang-rt/unittests/FortranRuntime/Random.cpp → flang/unittests/Runtime/Random.cpp
diff --git a/...rt/unittests/FortranRuntime/Reduction.cpp → flang/unittests/Runtime/Reduction.cpp b/...rt/unittests/FortranRuntime/Reduction.cpp → flang/unittests/Runtime/Reduction.cpp
diff --git a/...tests/FortranRuntime/RuntimeCrashTest.cpp → flang/unittests/Runtime/RuntimeCrashTest.cpp b/...tests/FortranRuntime/RuntimeCrashTest.cpp → flang/unittests/Runtime/RuntimeCrashTest.cpp
@@ -11,10 +11,10 @@
 //
 //===----------------------------------------------------------------------===//
 #include "CrashHandlerFixture.h"
-#include "flang/../../runtime/terminator.h"
+#include "tools.h"
+#include "../../runtime/terminator.h"
 #include "flang/Runtime/io-api.h"
 #include "flang/Runtime/transformational.h"
-#include "tools.h"
 #include <gtest/gtest.h>
 
 using namespace Fortran::runtime;
@@ -26,7 +26,7 @@ using Fortran::common::TypeCategory;
 //------------------------------------------------------------------------------
 struct TestTerminator : CrashHandlerFixture {};
 
-#define TEST_CRASH_HANDLER_MESSAGE                                             \
+#define TEST_CRASH_HANDLER_MESSAGE \
   "Intentionally crashing runtime for unit test"
 
 TEST(TestTerminator, CrashTest) {
@@ -39,13 +39,13 @@ TEST(TestTerminator, CrashTest) {
 TEST(TestTerminator, CheckFailedLocationTest) {
   static Fortran::runtime::Terminator t;
   ASSERT_DEATH(t.CheckFailed("predicate", "someFileName", 789),
-               "RUNTIME_CHECK\\(predicate\\) failed at someFileName\\(789\\)");
+      "RUNTIME_CHECK\\(predicate\\) failed at someFileName\\(789\\)");
 }
 
 TEST(TestTerminator, CheckFailedTest) {
   static Fortran::runtime::Terminator t;
   ASSERT_DEATH(t.CheckFailed("predicate"),
-               "RUNTIME_CHECK\\(predicate\\) failed at \\(null\\)\\(0\\)");
+      "RUNTIME_CHECK\\(predicate\\) failed at \\(null\\)\\(0\\)");
 }
 
 //------------------------------------------------------------------------------
@@ -57,21 +57,20 @@ TEST(TestIOCrash, FormatDescriptorWriteMismatchTest) {
   static constexpr int bufferSize{4};
   static char buffer[bufferSize];
   static const char *format{"(A4)"};
-  auto *cookie{IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                    std::strlen(format))};
-  ASSERT_DEATH(
-      IONAME(OutputLogical)(cookie, true),
+  auto *cookie{IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format))};
+  ASSERT_DEATH(IONAME(OutputLogical)(cookie, true),
       "Data edit descriptor 'A' may not be used with a LOGICAL data item");
 }
 
 TEST(TestIOCrash, InvalidFormatCharacterTest) {
   static constexpr int bufferSize{1};
   static char buffer[bufferSize];
   static const char *format{"(C1)"};
-  auto *cookie{IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                    std::strlen(format))};
+  auto *cookie{IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format))};
   ASSERT_DEATH(IONAME(OutputInteger64)(cookie, 0xfeedface),
-               "Unknown 'C' edit descriptor in FORMAT");
+      "Unknown 'C' edit descriptor in FORMAT");
 }
 
 //------------------------------------------------------------------------------
@@ -84,80 +83,80 @@ TEST(TestIOCrash, OverwriteBufferAsciiTest) {
   static constexpr int bufferSize{4};
   static char buffer[bufferSize];
   static const char *format{"(A4)"};
-  auto *cookie{IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                    std::strlen(format))};
+  auto *cookie{IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format))};
   IONAME(OutputAscii)(cookie, "four", bufferSize);
   ASSERT_DEATH(IONAME(OutputAscii)(cookie, "Too many characters!", 20),
-               "Internal write overran available records");
+      "Internal write overran available records");
 }
 
 TEST(TestIOCrash, OverwriteBufferCharacterTest) {
   static constexpr int bufferSize{1};
   static char buffer[bufferSize];
   static const char *format{"(A1)"};
-  auto *cookie{IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                    std::strlen(format))};
+  auto *cookie{IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format))};
   IONAME(OutputCharacter)(cookie, "a", 1);
   ASSERT_DEATH(IONAME(OutputCharacter)(cookie, "a", 1),
-               "Internal write overran available records");
+      "Internal write overran available records");
 }
 
 TEST(TestIOCrash, OverwriteBufferLogicalTest) {
   static constexpr int bufferSize{1};
   static char buffer[bufferSize];
   static const char *format{"(L1)"};
-  auto *cookie{IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                    std::strlen(format))};
+  auto *cookie{IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format))};
   IONAME(OutputLogical)(cookie, true);
   ASSERT_DEATH(IONAME(OutputLogical)(cookie, true),
-               "Internal write overran available records");
+      "Internal write overran available records");
 }
 
 TEST(TestIOCrash, OverwriteBufferRealTest) {
   static constexpr int bufferSize{1};
   static char buffer[bufferSize];
   static const char *format{"(F1)"};
-  auto *cookie{IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                    std::strlen(format))};
+  auto *cookie{IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format))};
   IONAME(OutputReal32)(cookie, 1.);
   EXPECT_DEATH(IONAME(OutputReal32)(cookie, 1.),
-               "Internal write overran available records");
+      "Internal write overran available records");
 
   std::memset(buffer, '\0', bufferSize);
-  cookie = IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                std::strlen(format));
+  cookie = IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format));
   IONAME(OutputReal64)(cookie, 1.);
   EXPECT_DEATH(IONAME(OutputReal64)(cookie, 1.),
-               "Internal write overran available records");
+      "Internal write overran available records");
 }
 
 TEST(TestIOCrash, OverwriteBufferComplexTest) {
   static constexpr int bufferSize{8};
   static char buffer[bufferSize];
   static const char *format{"(Z1,Z1)"};
-  auto *cookie{IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                    std::strlen(format))};
+  auto *cookie{IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format))};
   IONAME(OutputComplex32)(cookie, 1., 1.);
   EXPECT_DEATH(IONAME(OutputComplex32)(cookie, 1., 1.),
-               "Internal write overran available records");
+      "Internal write overran available records");
 
   std::memset(buffer, '\0', bufferSize);
-  cookie = IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                std::strlen(format));
+  cookie = IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format));
   IONAME(OutputComplex64)(cookie, 1., 1.);
   EXPECT_DEATH(IONAME(OutputComplex64)(cookie, 1., 1.),
-               "Internal write overran available records");
+      "Internal write overran available records");
 }
 
 TEST(TestIOCrash, OverwriteBufferIntegerTest) {
   static constexpr int bufferSize{1};
   static char buffer[bufferSize];
   static const char *format{"(I1)"};
-  auto *cookie{IONAME(BeginInternalFormattedOutput)(buffer, bufferSize, format,
-                                                    std::strlen(format))};
+  auto *cookie{IONAME(BeginInternalFormattedOutput)(
+      buffer, bufferSize, format, std::strlen(format))};
   IONAME(OutputInteger64)(cookie, 0xdeadbeef);
   ASSERT_DEATH(IONAME(OutputInteger64)(cookie, 0xdeadbeef),
-               "Internal write overran available records");
+      "Internal write overran available records");
 }
 
 //------------------------------------------------------------------------------
@@ -169,15 +168,13 @@ TEST(TestIntrinsicCrash, ConformityErrors) {
   // ARRAY(2,3) and MASK(2,4) should trigger a runtime error.
   auto array{MakeArray<TypeCategory::Integer, 4>(
       std::vector<int>{2, 3}, std::vector<std::int32_t>{1, 2, 3, 4, 5, 6})};
-  auto mask{MakeArray<TypeCategory::Logical, 1>(
-      std::vector<int>{2, 4},
-      std::vector<std::uint8_t>{false, true, true, false, false, true, true,
-                                true})};
+  auto mask{MakeArray<TypeCategory::Logical, 1>(std::vector<int>{2, 4},
+      std::vector<std::uint8_t>{
+          false, true, true, false, false, true, true, true})};
   StaticDescriptor<1, true> statDesc;
   Descriptor &result{statDesc.descriptor()};
 
-  ASSERT_DEATH(
-      RTNAME(Pack)(result, *array, *mask, nullptr, __FILE__, __LINE__),
+  ASSERT_DEATH(RTNAME(Pack)(result, *array, *mask, nullptr, __FILE__, __LINE__),
       "Incompatible array arguments to PACK: dimension 2 of ARRAY= has extent "
       "3 but MASK= has extent 4");
 }
diff --git a/flang-rt/unittests/FortranRuntime/Stop.cpp → flang/unittests/Runtime/Stop.cpp b/flang-rt/unittests/FortranRuntime/Stop.cpp → flang/unittests/Runtime/Stop.cpp
@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 #include "flang/Runtime/stop.h"
 #include "CrashHandlerFixture.h"
-#include "flang/../../runtime/environment.h"
+#include "../../runtime/environment.h"
 #include <cstdlib>
 #include <gtest/gtest.h>
 
@@ -21,69 +21,67 @@ struct TestProgramEnd : CrashHandlerFixture {};
 
 TEST(TestProgramEnd, StopTest) {
   EXPECT_EXIT(RTNAME(StopStatement)(), testing::ExitedWithCode(EXIT_SUCCESS),
-              "Fortran STOP");
+      "Fortran STOP");
 }
 
 TEST(TestProgramEnd, StopTestNoStopMessage) {
   putenv(const_cast<char *>("NO_STOP_MESSAGE=1"));
-  Fortran::runtime::executionEnvironment.Configure(0, nullptr, nullptr,
-                                                   nullptr);
-  EXPECT_EXIT(RTNAME(StopStatement)(), testing::ExitedWithCode(EXIT_SUCCESS),
-              "");
+  Fortran::runtime::executionEnvironment.Configure(
+      0, nullptr, nullptr, nullptr);
+  EXPECT_EXIT(
+      RTNAME(StopStatement)(), testing::ExitedWithCode(EXIT_SUCCESS), "");
 }
 
 TEST(TestProgramEnd, StopMessageTest) {
   static const char *message{"bye bye"};
   EXPECT_EXIT(RTNAME(StopStatementText)(message, std::strlen(message),
-                                        /*isErrorStop=*/false, /*quiet=*/false),
-              testing::ExitedWithCode(EXIT_SUCCESS), "Fortran STOP: bye bye");
+                  /*isErrorStop=*/false, /*quiet=*/false),
+      testing::ExitedWithCode(EXIT_SUCCESS), "Fortran STOP: bye bye");
 
   EXPECT_EXIT(RTNAME(StopStatementText)(message, std::strlen(message),
-                                        /*isErrorStop=*/false, /*quiet=*/true),
-              testing::ExitedWithCode(EXIT_SUCCESS), "");
+                  /*isErrorStop=*/false, /*quiet=*/true),
+      testing::ExitedWithCode(EXIT_SUCCESS), "");
 
   EXPECT_EXIT(RTNAME(StopStatementText)(message, std::strlen(message),
-                                        /*isErrorStop=*/true, /*quiet=*/false),
-              testing::ExitedWithCode(EXIT_FAILURE),
-              "Fortran ERROR STOP: bye bye");
+                  /*isErrorStop=*/true, /*quiet=*/false),
+      testing::ExitedWithCode(EXIT_FAILURE), "Fortran ERROR STOP: bye bye");
 
   EXPECT_EXIT(RTNAME(StopStatementText)(message, std::strlen(message),
-                                        /*isErrorStop=*/true, /*quiet=*/true),
-              testing::ExitedWithCode(EXIT_FAILURE), "");
+                  /*isErrorStop=*/true, /*quiet=*/true),
+      testing::ExitedWithCode(EXIT_FAILURE), "");
 }
 
 TEST(TestProgramEnd, NoStopMessageTest) {
   putenv(const_cast<char *>("NO_STOP_MESSAGE=1"));
-  Fortran::runtime::executionEnvironment.Configure(0, nullptr, nullptr,
-                                                   nullptr);
+  Fortran::runtime::executionEnvironment.Configure(
+      0, nullptr, nullptr, nullptr);
   static const char *message{"bye bye"};
   EXPECT_EXIT(RTNAME(StopStatementText)(message, std::strlen(message),
-                                        /*isErrorStop=*/false, /*quiet=*/false),
-              testing::ExitedWithCode(EXIT_SUCCESS), "bye bye");
+                  /*isErrorStop=*/false, /*quiet=*/false),
+      testing::ExitedWithCode(EXIT_SUCCESS), "bye bye");
 
   EXPECT_EXIT(RTNAME(StopStatementText)(message, std::strlen(message),
-                                        /*isErrorStop=*/false, /*quiet=*/true),
-              testing::ExitedWithCode(EXIT_SUCCESS), "");
+                  /*isErrorStop=*/false, /*quiet=*/true),
+      testing::ExitedWithCode(EXIT_SUCCESS), "");
 
   EXPECT_EXIT(RTNAME(StopStatementText)(message, std::strlen(message),
-                                        /*isErrorStop=*/true, /*quiet=*/false),
-              testing::ExitedWithCode(EXIT_FAILURE),
-              "Fortran ERROR STOP: bye bye");
+                  /*isErrorStop=*/true, /*quiet=*/false),
+      testing::ExitedWithCode(EXIT_FAILURE), "Fortran ERROR STOP: bye bye");
 
   EXPECT_EXIT(RTNAME(StopStatementText)(message, std::strlen(message),
-                                        /*isErrorStop=*/true, /*quiet=*/true),
-              testing::ExitedWithCode(EXIT_FAILURE), "");
+                  /*isErrorStop=*/true, /*quiet=*/true),
+      testing::ExitedWithCode(EXIT_FAILURE), "");
 }
 
 TEST(TestProgramEnd, FailImageTest) {
-  EXPECT_EXIT(RTNAME(FailImageStatement)(),
-              testing::ExitedWithCode(EXIT_FAILURE), "");
+  EXPECT_EXIT(
+      RTNAME(FailImageStatement)(), testing::ExitedWithCode(EXIT_FAILURE), "");
 }
 
 TEST(TestProgramEnd, ExitTest) {
   EXPECT_EXIT(RTNAME(Exit)(), testing::ExitedWithCode(EXIT_SUCCESS), "");
-  EXPECT_EXIT(RTNAME(Exit)(EXIT_FAILURE), testing::ExitedWithCode(EXIT_FAILURE),
-              "");
+  EXPECT_EXIT(
+      RTNAME(Exit)(EXIT_FAILURE), testing::ExitedWithCode(EXIT_FAILURE), "");
 }
 
 TEST(TestProgramEnd, AbortTest) { EXPECT_DEATH(RTNAME(Abort)(), ""); }
@@ -93,8 +91,8 @@ TEST(TestProgramEnd, CrashTest) {
   static const std::string fileName{"file name"};
   static const std::string headMessage{"fatal Fortran runtime error\\("};
   static const std::string tailMessage{":343\\): "};
-  static const std::string fullMessage{headMessage + fileName + tailMessage +
-                                       crashMessage};
+  static const std::string fullMessage{
+      headMessage + fileName + tailMessage + crashMessage};
   EXPECT_DEATH(
       RTNAME(ReportFatalUserError)(crashMessage.c_str(), fileName.c_str(), 343),
       fullMessage.c_str());

diff --git a/...ittests/FortranRuntime/TemporaryStack.cpp → flang/unittests/Runtime/TemporaryStack.cpp b/...ittests/FortranRuntime/TemporaryStack.cpp → flang/unittests/Runtime/TemporaryStack.cpp
diff --git a/flang-rt/unittests/FortranRuntime/Time.cpp → flang/unittests/Runtime/Time.cpp b/flang-rt/unittests/FortranRuntime/Time.cpp → flang/unittests/Runtime/Time.cpp
diff --git a/...tests/FortranRuntime/Transformational.cpp → flang/unittests/Runtime/Transformational.cpp b/...tests/FortranRuntime/Transformational.cpp → flang/unittests/Runtime/Transformational.cpp
diff --git a/flang-rt/unittests/FortranRuntime/tools.h → flang/unittests/Runtime/tools.h b/flang-rt/unittests/FortranRuntime/tools.h → flang/unittests/Runtime/tools.h
diff --git a/lld/COFF/MinGW.cpp b/lld/COFF/MinGW.cpp
@@ -50,7 +50,8 @@ AutoExporter::AutoExporter(
       "libc++",
       "libc++abi",
       "libFortran_main",
-      "libflang-rt",
+      "libFortranRuntime",
+      "libFortranDecimal",
       "libunwind",
       "libmsvcrt",
       "libucrtbase",

diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
@@ -156,10 +156,7 @@ endif()
 # As we migrate runtimes to using the bootstrapping build, the set of default runtimes
 # should grow as we remove those runtimes from LLVM_ENABLE_PROJECTS above.
 set(LLVM_DEFAULT_RUNTIMES "libcxx;libcxxabi;libunwind")
-if ("flang" IN_LIST LLVM_ENABLE_PROJECTS)
-  set(LLVM_DEFAULT_RUNTIMES "libcxx;libcxxabi;libunwind;flang-rt")
-endif()
-set(LLVM_SUPPORTED_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;llvm-libgcc;flang-rt")
+set(LLVM_SUPPORTED_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;llvm-libgcc")
 set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
   "Semicolon-separated list of runtimes to build, or \"all\" (${LLVM_DEFAULT_RUNTIMES}). Supported runtimes are ${LLVM_SUPPORTED_RUNTIMES}.")
 if(LLVM_ENABLE_RUNTIMES STREQUAL "all")
@@ -181,11 +178,6 @@ if ("libc" IN_LIST LLVM_ENABLE_RUNTIMES)
   endif()
 endif()
 
-if ("flang" IN_LIST LLVM_ENABLE_PROJECTS AND NOT "flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
-  message(STATUS "Enabling Flang-rt to be built with the Flang project.")
-  list(APPEND LLVM_ENABLE_RUNTIMES "flang-rt")
-endif()
-
 # LLVM_ENABLE_PROJECTS_USED is `ON` if the user has ever used the
 # `LLVM_ENABLE_PROJECTS` CMake cache variable.  This exists for
 # several reasons:

diff --git a/llvm/projects/CMakeLists.txt b/llvm/projects/CMakeLists.txt
@@ -6,7 +6,6 @@ foreach(entry ${entries})
   if(IS_DIRECTORY ${entry} AND EXISTS ${entry}/CMakeLists.txt)
     if((NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/compiler-rt) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/dragonegg) AND
-       (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/flang-rt) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libcxx) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libcxxabi) AND
        (NOT ${entry} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR}/libunwind) AND
@@ -38,8 +37,6 @@ if(${LLVM_BUILD_RUNTIME})
   if(NOT LLVM_BUILD_EXTERNAL_COMPILER_RT)
     add_llvm_external_project(compiler-rt)
   endif()
-
-  add_llvm_external_project(flang-rt)
 endif()
 
 add_llvm_external_project(dragonegg)

diff --git a/llvm/runtimes/CMakeLists.txt b/llvm/runtimes/CMakeLists.txt
@@ -401,24 +401,17 @@ if(runtimes)
       endforeach()
     endif()
   endif()
-  set(EXTRA_CMAKE_ARGS "")
-  if("flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
-    list(APPEND EXTRA_CMAKE_ARGS "-DLLVM_DIR=${LLVM_BINARY_DIR}/lib/cmake/llvm")
-    list(APPEND EXTRA_CMAKE_ARGS "-DFLANG_DIR=${LLVM_BINARY_DIR}/lib/cmake/flang")
-    list(APPEND EXTRA_CMAKE_ARGS "-DCLANG_DIR=${LLVM_BINARY_DIR}/lib/cmake/clang")
-    list(APPEND EXTRA_CMAKE_ARGS "-DMLIR_DIR=${LLVM_BINARY_DIR}/lib/cmake/mlir")
-  endif()
   if(NOT LLVM_RUNTIME_TARGETS)
     runtime_default_target(
       DEPENDS ${builtins_dep} ${extra_deps}
-      CMAKE_ARGS ${libc_cmake_args} ${EXTRA_CMAKE_ARGS}
+      CMAKE_ARGS ${libc_cmake_args}
       PREFIXES ${prefixes})
     set(test_targets check-runtimes)
   else()
     if("default" IN_LIST LLVM_RUNTIME_TARGETS)
       runtime_default_target(
         DEPENDS ${builtins_dep} ${extra_deps}
-        CMAKE_ARGS ${libc_cmake_args} ${EXTRA_CMAKE_ARGS}
+        CMAKE_ARGS ${libc_cmake_args}
         PREFIXES ${prefixes})
       list(REMOVE_ITEM LLVM_RUNTIME_TARGETS "default")
     else()
@@ -458,7 +451,7 @@ if(runtimes)
 
       runtime_register_target(${name}
         DEPENDS ${builtins_dep_name} ${libc_tools}
-        CMAKE_ARGS -DLLVM_DEFAULT_TARGET_TRIPLE=${name} ${libc_cmake_args} ${EXTRA_CMAKE_ARGS}
+        CMAKE_ARGS -DLLVM_DEFAULT_TARGET_TRIPLE=${name} ${libc_cmake_args}
         EXTRA_ARGS TARGET_TRIPLE ${name})
 
       add_dependencies(runtimes runtimes-${name})
@@ -488,7 +481,6 @@ if(runtimes)
           CMAKE_ARGS -DLLVM_DEFAULT_TARGET_TRIPLE=${name}
                      -DLLVM_RUNTIMES_PREFIX=${name}/
                      -DLLVM_RUNTIMES_LIBDIR_SUBDIR=${multilib}
-                     ${EXTRA_CMAKE_ARGS}
           BASE_NAME ${name}
           EXTRA_ARGS TARGET_TRIPLE ${name})
 

diff --git a/runtimes/CMakeLists.txt b/runtimes/CMakeLists.txt
@@ -19,7 +19,7 @@ list(INSERT CMAKE_MODULE_PATH 0
 
 # We order libraries to mirror roughly how they are layered, except that compiler-rt can depend
 # on libc++, so we put it after.
-set(LLVM_DEFAULT_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;flang-rt")
+set(LLVM_DEFAULT_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp")
 set(LLVM_SUPPORTED_RUNTIMES "${LLVM_DEFAULT_RUNTIMES};llvm-libgcc")
 set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
   "Semicolon-separated list of runtimes to build, or \"all\" (${LLVM_DEFAULT_RUNTIMES}). Supported runtimes are ${LLVM_SUPPORTED_RUNTIMES}.")