diff --git a/integration_test/CMakeLists.txt b/integration_test/CMakeLists.txt
index b33d6eeb3a30..6d0782b2aafc 100644
--- a/integration_test/CMakeLists.txt
+++ b/integration_test/CMakeLists.txt
@@ -30,8 +30,6 @@ llvm_canonicalize_cmake_booleans(ESI_RUNTIME)
 if (ESI_RUNTIME)
   list(APPEND CIRCT_INTEGRATION_TEST_DEPENDS
     ESIRuntime
-    ESIPythonRuntime
-    esiquery
     esitester
   )
 
diff --git a/integration_test/lit.site.cfg.py.in b/integration_test/lit.site.cfg.py.in
index 4d63e8ff3b28..d3cd2c3fcf0d 100644
--- a/integration_test/lit.site.cfg.py.in
+++ b/integration_test/lit.site.cfg.py.in
@@ -49,7 +49,7 @@ config.iverilog_path = "@IVERILOG_PATH@"
 config.clang_tidy_path = "@CLANG_TIDY_PATH@"
 config.have_systemc = "@HAVE_SYSTEMC@"
 config.esi_runtime = "@ESI_RUNTIME@"
-config.esi_runtime_path = "@ESIRuntimePath@"
+config.esi_runtime_path = "@ESICppRuntimePath@"
 config.bindings_python_enabled = @CIRCT_BINDINGS_PYTHON_ENABLED@
 config.bindings_tcl_enabled = @CIRCT_BINDINGS_TCL_ENABLED@
 config.lec_enabled = "@CIRCT_LEC_ENABLED@"
diff --git a/lib/Dialect/ESI/runtime/CMakeLists.txt b/lib/Dialect/ESI/runtime/CMakeLists.txt
index adf2e1de0755..24d406e3bf0c 100644
--- a/lib/Dialect/ESI/runtime/CMakeLists.txt
+++ b/lib/Dialect/ESI/runtime/CMakeLists.txt
@@ -104,7 +104,7 @@ if(ESI_COSIM)
     find_package(gRPC REQUIRED CONFIG)
   endif()
 
-  add_subdirectory(cosim)
+  add_subdirectory(cosim_dpi_server)
   # Inform the runtime code that Cosimulation is enabled. Kinda hacky since all
   # backends should only need to be linked in.
   # TODO: Once the hack in the python bindings is remidied, remove this.
@@ -112,18 +112,13 @@ if(ESI_COSIM)
   set(ESICppRuntimeSources
     ${ESICppRuntimeSources}
     ${CMAKE_CURRENT_SOURCE_DIR}/cpp/lib/backends/Cosim.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/cpp/lib/backends/RpcServer.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/cosim.proto
   )
   set(ESICppRuntimeBackendHeaders
     ${ESICppRuntimeBackendHeaders}
     ${CMAKE_CURRENT_SOURCE_DIR}/cpp/include/esi/backends/Cosim.h
-  )
-  set(ESICppRuntimeLinkLibraries
-    ${ESICppRuntimeLinkLibraries}
-    EsiCosimGRPC
-  )
-  set(ESICppRuntimeIncludeDirs
-    ${ESICppRuntimeIncludeDirs}
-    ${CMAKE_CURRENT_SOURCE_DIR}/cosim/include
+    ${CMAKE_CURRENT_SOURCE_DIR}/cpp/include/esi/backends/RpcServer.h
   )
 else()
   message("-- ESI cosim disabled")
@@ -198,6 +193,21 @@ if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
   target_compile_options(ESICppRuntime PRIVATE -Wno-covered-switch-default)
 endif()
 
+if(ESI_COSIM)
+  target_link_libraries(ESICppRuntime PUBLIC protobuf::libprotobuf gRPC::grpc++)
+  set(PROTO_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/generated")
+  target_include_directories(ESICppRuntime PUBLIC "$<BUILD_INTERFACE:${PROTO_BINARY_DIR}>")
+  protobuf_generate(
+      TARGET ESICppRuntime
+      PROTOC_OUT_DIR "${PROTO_BINARY_DIR}")
+  protobuf_generate(
+      TARGET ESICppRuntime
+      LANGUAGE grpc
+      GENERATE_EXTENSIONS .grpc.pb.h .grpc.pb.cc
+      PLUGIN "protoc-gen-grpc=\$<TARGET_FILE:gRPC::grpc_cpp_plugin>"
+      PROTOC_OUT_DIR "${PROTO_BINARY_DIR}")
+endif()
+
 # The esiquery tool is a simple wrapper around the SysInfo API.
 add_executable(esiquery
   ${CMAKE_CURRENT_SOURCE_DIR}/cpp/tools/esiquery.cpp
diff --git a/lib/Dialect/ESI/runtime/cosim/cosim.proto b/lib/Dialect/ESI/runtime/cosim.proto
similarity index 100%
rename from lib/Dialect/ESI/runtime/cosim/cosim.proto
rename to lib/Dialect/ESI/runtime/cosim.proto
diff --git a/lib/Dialect/ESI/runtime/cosim/CMakeLists.txt b/lib/Dialect/ESI/runtime/cosim/CMakeLists.txt
deleted file mode 100644
index c0a1e8857e47..000000000000
--- a/lib/Dialect/ESI/runtime/cosim/CMakeLists.txt
+++ /dev/null
@@ -1,70 +0,0 @@
-##===- CMakeLists.txt - ESI cosim support ---------------------*- cmake -*-===//
-##
-##===----------------------------------------------------------------------===//
-
-set(cosim_collateral
-  Cosim_DpiPkg.sv
-  Cosim_Endpoint.sv
-  Cosim_Manifest.sv
-  Cosim_MMIO.sv
-
-  driver.sv
-  driver.cpp
-)
-
-install(FILES
-  ${cosim_collateral}
-  DESTINATION cosim
-  COMPONENT ESIRuntime
-)
-
-add_custom_target(esi-cosim
-  COMMAND ${CMAKE_COMMAND} -E copy_if_different
-          ${CMAKE_CURRENT_SOURCE_DIR}/esi-cosim.py
-          ${CIRCT_TOOLS_DIR}/esi-cosim.py)
-foreach (cf ${cosim_collateral})
-  add_custom_command(TARGET esi-cosim POST_BUILD
-      COMMAND ${CMAKE_COMMAND} -E copy_if_different
-              ${CMAKE_CURRENT_SOURCE_DIR}/${cf}
-              ${CIRCT_TOOLS_DIR}/../cosim/${cf}
-  )
-endforeach()
-install(FILES
-  esi-cosim.py
-  DESTINATION bin
-  PERMISSIONS OWNER_EXECUTE OWNER_WRITE OWNER_READ
-              GROUP_EXECUTE GROUP_READ
-              WORLD_EXECUTE WORLD_READ
-  COMPONENT ESIRuntime
-)
-
-add_library(EsiCosimGRPC SHARED "${CMAKE_CURRENT_LIST_DIR}/cosim.proto")
-install(TARGETS EsiCosimGRPC DESTINATION lib COMPONENT ESIRuntime)
-target_link_libraries(EsiCosimGRPC PUBLIC protobuf::libprotobuf gRPC::grpc++)
-set(PROTO_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/generated")
-target_include_directories(EsiCosimGRPC PUBLIC "$<BUILD_INTERFACE:${PROTO_BINARY_DIR}>")
-
-protobuf_generate(
-    TARGET EsiCosimGRPC
-    PROTOC_OUT_DIR "${PROTO_BINARY_DIR}")
-protobuf_generate(
-    TARGET EsiCosimGRPC
-    LANGUAGE grpc
-    GENERATE_EXTENSIONS .grpc.pb.h .grpc.pb.cc
-    PLUGIN "protoc-gen-grpc=\$<TARGET_FILE:gRPC::grpc_cpp_plugin>"
-    PROTOC_OUT_DIR "${PROTO_BINARY_DIR}")
-
-include_directories("${CMAKE_CURRENT_SOURCE_DIR}/include")
-
-add_library(CosimRpcServer SHARED
-  lib/RpcServer.cpp
-)
-target_link_libraries(CosimRpcServer
-  PUBLIC
-  EsiCosimGRPC
-  ESICppRuntime
-)
-install(TARGETS CosimRpcServer DESTINATION lib COMPONENT ESIRuntime)
-
-add_subdirectory(cosim_dpi_server)
-add_subdirectory(MtiPliStub)
diff --git a/lib/Dialect/ESI/runtime/cosim/MtiPliStub/CMakeLists.txt b/lib/Dialect/ESI/runtime/cosim/MtiPliStub/CMakeLists.txt
deleted file mode 100644
index 6fc2a9749f0a..000000000000
--- a/lib/Dialect/ESI/runtime/cosim/MtiPliStub/CMakeLists.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-set(SOURCES ${CAPNP_SRCS} DummySvDpi.cpp )
-add_library(MtiPli SHARED ${SOURCES})
-target_include_directories(MtiPli PRIVATE ${CIRCT_INCLUDE_DIR})
-set_target_properties(MtiPli PROPERTIES CXX_VISIBILITY_PRESET "default")
-install(TARGETS MtiPli
-  DESTINATION lib
-  COMPONENT ESIRuntime
-)
diff --git a/lib/Dialect/ESI/runtime/cosim/cosim_dpi_server/CMakeLists.txt b/lib/Dialect/ESI/runtime/cosim/cosim_dpi_server/CMakeLists.txt
deleted file mode 100644
index cf7de4c4c477..000000000000
--- a/lib/Dialect/ESI/runtime/cosim/cosim_dpi_server/CMakeLists.txt
+++ /dev/null
@@ -1,30 +0,0 @@
-##===- CMakeLists.txt - Core cosim DPI library ----------------*- cmake -*-===//
-##
-## Define the cosim DPI library if it's enabled.
-##
-##===----------------------------------------------------------------------===//
-
-add_library(EsiCosimDpiServer SHARED
-  DpiEntryPoints.cpp
-)
-set_target_properties(EsiCosimDpiServer
-    PROPERTIES
-        LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib
-        RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib
-        CXX_VISIBILITY_PRESET "default"
-)
-add_dependencies(EsiCosimDpiServer ESICppRuntime MtiPli)
-target_link_libraries(EsiCosimDpiServer
-  PUBLIC
-    ESICppRuntime
-    CosimRpcServer
-    MtiPli
-)
-
-install(TARGETS EsiCosimDpiServer
-  DESTINATION lib
-  COMPONENT ESIRuntime
-)
-
-set(ESI_COSIM_PATH $<TARGET_FILE:EsiCosimDpiServer>
-      CACHE PATH "Path to Cosim DPI shared library")
diff --git a/lib/Dialect/ESI/runtime/cosim_dpi_server/CMakeLists.txt b/lib/Dialect/ESI/runtime/cosim_dpi_server/CMakeLists.txt
new file mode 100644
index 000000000000..154968ae5def
--- /dev/null
+++ b/lib/Dialect/ESI/runtime/cosim_dpi_server/CMakeLists.txt
@@ -0,0 +1,75 @@
+##===- CMakeLists.txt - Core cosim DPI library ----------------*- cmake -*-===//
+##
+## Define the cosim DPI library if it's enabled.
+##
+##===----------------------------------------------------------------------===//
+
+# Dummy library for a library which should be included by the RTL simulator.
+# Dummy is necessary for linking purposes. NOT to be distributed.
+add_library(MtiPli SHARED
+  DummySvDpi.cpp
+)
+set_target_properties(MtiPli PROPERTIES CXX_VISIBILITY_PRESET "default")
+
+# DPI calls.
+add_library(EsiCosimDpiServer SHARED
+  DpiEntryPoints.cpp
+)
+set_target_properties(EsiCosimDpiServer
+    PROPERTIES
+        LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib
+        RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib
+        CXX_VISIBILITY_PRESET "default"
+)
+add_dependencies(EsiCosimDpiServer ESICppRuntime MtiPli)
+target_link_libraries(EsiCosimDpiServer
+  PUBLIC
+    ESICppRuntime
+    MtiPli
+)
+
+install(TARGETS EsiCosimDpiServer
+  DESTINATION lib
+  COMPONENT ESIRuntime
+)
+
+# RTL cosimulation collateral.
+set(cosim_collateral
+  Cosim_DpiPkg.sv
+  Cosim_Endpoint.sv
+  Cosim_Manifest.sv
+  Cosim_MMIO.sv
+
+  driver.sv
+  driver.cpp
+)
+
+install(FILES
+  ${cosim_collateral}
+  DESTINATION cosim
+  COMPONENT ESIRuntime
+)
+
+add_custom_target(esi-cosim
+  COMMAND ${CMAKE_COMMAND} -E copy_if_different
+          ${CMAKE_CURRENT_SOURCE_DIR}/esi-cosim.py
+          ${CIRCT_TOOLS_DIR}/esi-cosim.py)
+foreach (cf ${cosim_collateral})
+  add_custom_command(TARGET esi-cosim POST_BUILD
+      COMMAND ${CMAKE_COMMAND} -E copy_if_different
+              ${CMAKE_CURRENT_SOURCE_DIR}/${cf}
+              ${CIRCT_TOOLS_DIR}/../cosim/${cf}
+  )
+endforeach()
+
+# ESI simple cosim runner.
+install(FILES
+  esi-cosim.py
+  DESTINATION bin
+  PERMISSIONS OWNER_EXECUTE OWNER_WRITE OWNER_READ
+              GROUP_EXECUTE GROUP_READ
+              WORLD_EXECUTE WORLD_READ
+  COMPONENT ESIRuntime
+)
+set(ESI_COSIM_PATH $<TARGET_FILE:EsiCosimDpiServer>
+      CACHE PATH "Path to Cosim DPI shared library")
diff --git a/lib/Dialect/ESI/runtime/cosim/Cosim_DpiPkg.sv b/lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_DpiPkg.sv
similarity index 100%
rename from lib/Dialect/ESI/runtime/cosim/Cosim_DpiPkg.sv
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_DpiPkg.sv
diff --git a/lib/Dialect/ESI/runtime/cosim/Cosim_Endpoint.sv b/lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_Endpoint.sv
similarity index 100%
rename from lib/Dialect/ESI/runtime/cosim/Cosim_Endpoint.sv
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_Endpoint.sv
diff --git a/lib/Dialect/ESI/runtime/cosim/Cosim_MMIO.sv b/lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_MMIO.sv
similarity index 100%
rename from lib/Dialect/ESI/runtime/cosim/Cosim_MMIO.sv
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_MMIO.sv
diff --git a/lib/Dialect/ESI/runtime/cosim/Cosim_Manifest.sv b/lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_Manifest.sv
similarity index 100%
rename from lib/Dialect/ESI/runtime/cosim/Cosim_Manifest.sv
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/Cosim_Manifest.sv
diff --git a/lib/Dialect/ESI/runtime/cosim/cosim_dpi_server/DpiEntryPoints.cpp b/lib/Dialect/ESI/runtime/cosim_dpi_server/DpiEntryPoints.cpp
similarity index 99%
rename from lib/Dialect/ESI/runtime/cosim/cosim_dpi_server/DpiEntryPoints.cpp
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/DpiEntryPoints.cpp
index 460d2782fccc..b349e75c509b 100644
--- a/lib/Dialect/ESI/runtime/cosim/cosim_dpi_server/DpiEntryPoints.cpp
+++ b/lib/Dialect/ESI/runtime/cosim_dpi_server/DpiEntryPoints.cpp
@@ -18,7 +18,7 @@
 
 #include "dpi.h"
 #include "esi/Ports.h"
-#include "esi/cosim/RpcServer.h"
+#include "esi/backends/RpcServer.h"
 
 #include <algorithm>
 #include <cassert>
diff --git a/lib/Dialect/ESI/runtime/cosim/MtiPliStub/DummySvDpi.cpp b/lib/Dialect/ESI/runtime/cosim_dpi_server/DummySvDpi.cpp
similarity index 99%
rename from lib/Dialect/ESI/runtime/cosim/MtiPliStub/DummySvDpi.cpp
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/DummySvDpi.cpp
index bc40cbb352ab..060193e4a926 100644
--- a/lib/Dialect/ESI/runtime/cosim/MtiPliStub/DummySvDpi.cpp
+++ b/lib/Dialect/ESI/runtime/cosim_dpi_server/DummySvDpi.cpp
@@ -20,7 +20,7 @@
 #undef EETERN
 #define EETERN DPI_EXTERN DPI_DLLESPEC
 
-#include "dpi/svdpi.h"
+#include "svdpi.h"
 #undef NDEBUG
 #include <cassert>
 
diff --git a/lib/Dialect/ESI/runtime/cosim/cosim_dpi_server/dpi.h b/lib/Dialect/ESI/runtime/cosim_dpi_server/dpi.h
similarity index 99%
rename from lib/Dialect/ESI/runtime/cosim/cosim_dpi_server/dpi.h
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/dpi.h
index 2713746527d6..7e353dc04d1d 100644
--- a/lib/Dialect/ESI/runtime/cosim/cosim_dpi_server/dpi.h
+++ b/lib/Dialect/ESI/runtime/cosim_dpi_server/dpi.h
@@ -15,7 +15,7 @@
 #ifndef CIRCT_DIALECT_ESI_COSIM_DPI_H
 #define CIRCT_DIALECT_ESI_COSIM_DPI_H
 
-#include "dpi/svdpi.h"
+#include "svdpi.h"
 
 #ifdef WIN32
 #define DPI extern "C" __declspec(dllexport)
diff --git a/lib/Dialect/ESI/runtime/cosim/driver.cpp b/lib/Dialect/ESI/runtime/cosim_dpi_server/driver.cpp
similarity index 100%
rename from lib/Dialect/ESI/runtime/cosim/driver.cpp
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/driver.cpp
diff --git a/lib/Dialect/ESI/runtime/cosim/driver.sv b/lib/Dialect/ESI/runtime/cosim_dpi_server/driver.sv
similarity index 100%
rename from lib/Dialect/ESI/runtime/cosim/driver.sv
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/driver.sv
diff --git a/lib/Dialect/ESI/runtime/cosim/esi-cosim.py b/lib/Dialect/ESI/runtime/cosim_dpi_server/esi-cosim.py
similarity index 100%
rename from lib/Dialect/ESI/runtime/cosim/esi-cosim.py
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/esi-cosim.py
diff --git a/lib/Dialect/ESI/runtime/cosim/include/dpi/svdpi.h b/lib/Dialect/ESI/runtime/cosim_dpi_server/svdpi.h
similarity index 100%
rename from lib/Dialect/ESI/runtime/cosim/include/dpi/svdpi.h
rename to lib/Dialect/ESI/runtime/cosim_dpi_server/svdpi.h
diff --git a/lib/Dialect/ESI/runtime/cosim/include/esi/cosim/RpcServer.h b/lib/Dialect/ESI/runtime/cpp/include/esi/backends/RpcServer.h
similarity index 96%
rename from lib/Dialect/ESI/runtime/cosim/include/esi/cosim/RpcServer.h
rename to lib/Dialect/ESI/runtime/cpp/include/esi/backends/RpcServer.h
index bbfc694c4c20..22d4e9a9233c 100644
--- a/lib/Dialect/ESI/runtime/cosim/include/esi/cosim/RpcServer.h
+++ b/lib/Dialect/ESI/runtime/cpp/include/esi/backends/RpcServer.h
@@ -21,6 +21,7 @@
 namespace esi {
 namespace cosim {
 
+/// TODO: make this a proper backend (as much as possible).
 class RpcServer {
 public:
   ~RpcServer();
diff --git a/lib/Dialect/ESI/runtime/cosim/lib/RpcServer.cpp b/lib/Dialect/ESI/runtime/cpp/lib/backends/RpcServer.cpp
similarity index 99%
rename from lib/Dialect/ESI/runtime/cosim/lib/RpcServer.cpp
rename to lib/Dialect/ESI/runtime/cpp/lib/backends/RpcServer.cpp
index 1026e1bbd594..341b7b40a5b1 100644
--- a/lib/Dialect/ESI/runtime/cosim/lib/RpcServer.cpp
+++ b/lib/Dialect/ESI/runtime/cpp/lib/backends/RpcServer.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "esi/cosim/RpcServer.h"
+#include "esi/backends/RpcServer.h"
 #include "esi/Utils.h"
 
 #include "cosim.grpc.pb.h"