Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -550,9 +550,13 @@
     "Semicolon-separated list of components to include in libLLVM, or \"all\".")
 endif()
 option(LLVM_LINK_LLVM_DYLIB "Link tools against the libllvm dynamic library" OFF)
-option(LLVM_BUILD_LLVM_C_DYLIB "Build libllvm-c re-export library (Darwin Only)" OFF)
+if(MSVC)
+  option(LLVM_BUILD_LLVM_C_DYLIB "Build LLVM-C.dll (Windows only)" OFF)
+else()
+  option(LLVM_BUILD_LLVM_C_DYLIB "Build libllvm-c re-export library (Darwin only)" OFF)
+endif()
 set(LLVM_BUILD_LLVM_DYLIB_default OFF)
-if(LLVM_LINK_LLVM_DYLIB OR LLVM_BUILD_LLVM_C_DYLIB)
+if(LLVM_LINK_LLVM_DYLIB OR (LLVM_BUILD_LLVM_C_DYLIB AND NOT MSVC))
   set(LLVM_BUILD_LLVM_DYLIB_default ON)
 endif()
 option(LLVM_BUILD_LLVM_DYLIB "Build libllvm dynamic library" ${LLVM_BUILD_LLVM_DYLIB_default})
Index: tools/CMakeLists.txt
===================================================================
--- tools/CMakeLists.txt
+++ tools/CMakeLists.txt
@@ -17,7 +17,7 @@
   set(LLVM_TOOL_POLLY_BUILD Off)
 endif()
 
-if(NOT LLVM_BUILD_LLVM_DYLIB )
+if(NOT LLVM_BUILD_LLVM_DYLIB AND NOT LLVM_BUILD_LLVM_C_DYLIB)
   set(LLVM_TOOL_LLVM_SHLIB_BUILD Off)
 endif()
 
Index: tools/llvm-shlib/CMakeLists.txt
===================================================================
--- tools/llvm-shlib/CMakeLists.txt
+++ tools/llvm-shlib/CMakeLists.txt
@@ -6,77 +6,87 @@
   libllvm.cpp
   )
 
-llvm_map_components_to_libnames(LIB_NAMES ${LLVM_DYLIB_COMPONENTS})
-
 if(LLVM_LINK_LLVM_DYLIB AND LLVM_DYLIB_EXPORTED_SYMBOL_FILE)
   message(WARNING "Using LLVM_LINK_LLVM_DYLIB with LLVM_DYLIB_EXPORTED_SYMBOL_FILE may not work. Use at your own risk.")
 endif()
 
-# libLLVM.so should not have any dependencies on any other LLVM
-# shared libraries. When using the "all" pseudo-component,
-# LLVM_AVAILABLE_LIBS is added to the dependencies, which may
-# contain shared libraries (e.g. libLTO).
-#
-# Also exclude libLLVMTableGen for the following reasons:
-#  - it is only used by internal *-tblgen utilities;
-#  - it pollutes the global options space.
-foreach(lib ${LIB_NAMES})
-  get_target_property(t ${lib} TYPE)
-  if("${lib}" STREQUAL "LLVMTableGen")
-  elseif("x${t}" STREQUAL "xSTATIC_LIBRARY")
-    list(APPEND FILTERED_LIB_NAMES ${lib})
+if(LLVM_BUILD_LLVM_DYLIB)
+  if(MSVC)
+    message(FATAL_ERROR "Generating libLLVM is not supported on MSVC")
   endif()
-endforeach()
-set(LIB_NAMES ${FILTERED_LIB_NAMES})
 
-if(LLVM_DYLIB_EXPORTED_SYMBOL_FILE)
-  set(LLVM_EXPORTED_SYMBOL_FILE ${LLVM_DYLIB_EXPORTED_SYMBOL_FILE})
-  add_custom_target(libLLVMExports DEPENDS ${LLVM_EXPORTED_SYMBOL_FILE})
-endif()
+  llvm_map_components_to_libnames(LIB_NAMES ${LLVM_DYLIB_COMPONENTS})
+
+  # libLLVM.so should not have any dependencies on any other LLVM
+  # shared libraries. When using the "all" pseudo-component,
+  # LLVM_AVAILABLE_LIBS is added to the dependencies, which may
+  # contain shared libraries (e.g. libLTO).
+  #
+  # Also exclude libLLVMTableGen for the following reasons:
+  #  - it is only used by internal *-tblgen utilities;
+  #  - it pollutes the global options space.
+  foreach(lib ${LIB_NAMES})
+    get_target_property(t ${lib} TYPE)
+    if("${lib}" STREQUAL "LLVMTableGen")
+    elseif("x${t}" STREQUAL "xSTATIC_LIBRARY")
+      list(APPEND FILTERED_LIB_NAMES ${lib})
+    endif()
+  endforeach()
+  set(LIB_NAMES ${FILTERED_LIB_NAMES})
+
+  if(LLVM_DYLIB_EXPORTED_SYMBOL_FILE)
+    set(LLVM_EXPORTED_SYMBOL_FILE ${LLVM_DYLIB_EXPORTED_SYMBOL_FILE})
+    add_custom_target(libLLVMExports DEPENDS ${LLVM_EXPORTED_SYMBOL_FILE})
+  endif()
 
-add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB SONAME ${SOURCES})
-
-list(REMOVE_DUPLICATES LIB_NAMES)
-if(("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux") OR (MINGW) OR (HAIKU)
-   OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "FreeBSD")
-   OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "OpenBSD")
-   OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "Fuchsia")
-   OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "DragonFly")
-   OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "SunOS")) # FIXME: It should be "GNU ld for elf"
-  configure_file(
-  ${CMAKE_CURRENT_SOURCE_DIR}/simple_version_script.map.in
-  ${LLVM_LIBRARY_DIR}/tools/llvm-shlib/simple_version_script.map)
-
-  # GNU ld doesn't resolve symbols in the version script.
-  set(LIB_NAMES -Wl,--whole-archive ${LIB_NAMES} -Wl,--no-whole-archive)
-  if (NOT LLVM_LINKER_IS_SOLARISLD)
-    # Solaris ld does not accept global: *; so there is no way to version *all* global symbols
-    set(LIB_NAMES -Wl,--version-script,${LLVM_LIBRARY_DIR}/tools/llvm-shlib/simple_version_script.map ${LIB_NAMES})
+  add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB SONAME ${SOURCES})
+
+  list(REMOVE_DUPLICATES LIB_NAMES)
+  if(("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux") OR (MINGW) OR (HAIKU)
+     OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "FreeBSD")
+     OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "OpenBSD")
+     OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "Fuchsia")
+     OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "DragonFly")
+     OR ("${CMAKE_SYSTEM_NAME}" STREQUAL "SunOS")) # FIXME: It should be "GNU ld for elf"
+    configure_file(
+    ${CMAKE_CURRENT_SOURCE_DIR}/simple_version_script.map.in
+    ${LLVM_LIBRARY_DIR}/tools/llvm-shlib/simple_version_script.map)
+
+    # GNU ld doesn't resolve symbols in the version script.
+    set(LIB_NAMES -Wl,--whole-archive ${LIB_NAMES} -Wl,--no-whole-archive)
+    if (NOT LLVM_LINKER_IS_SOLARISLD)
+      # Solaris ld does not accept global: *; so there is no way to version *all* global symbols
+      set(LIB_NAMES -Wl,--version-script,${LLVM_LIBRARY_DIR}/tools/llvm-shlib/simple_version_script.map ${LIB_NAMES})
+    endif()
+  elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
+    set(LIB_NAMES -Wl,-all_load ${LIB_NAMES})
   endif()
-elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
-  set(LIB_NAMES -Wl,-all_load ${LIB_NAMES})
-endif()
 
-target_link_libraries(LLVM PRIVATE ${LIB_NAMES})
+  target_link_libraries(LLVM PRIVATE ${LIB_NAMES})
 
-if (APPLE)
-  set_property(TARGET LLVM APPEND_STRING PROPERTY
-              LINK_FLAGS
-              " -compatibility_version 1 -current_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}")
-endif()
+  if (APPLE)
+    set_property(TARGET LLVM APPEND_STRING PROPERTY
+                LINK_FLAGS
+                " -compatibility_version 1 -current_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}")
+  endif()
 
-if(TARGET libLLVMExports)
-  add_dependencies(LLVM libLLVMExports)
+  if(TARGET libLLVMExports)
+    add_dependencies(LLVM libLLVMExports)
+  endif()
 endif()
 
-if(LLVM_BUILD_LLVM_C_DYLIB)
-  # To get the export list for a single llvm library:
-  # nm ${LIB_PATH} | awk "/T _LLVM/ { print $3 }" | sort -u | sed -e "s/^_//g" > ${LIB_PATH}.exports
-
+if(LLVM_BUILD_LLVM_C_DYLIB AND NOT MSVC)
   if(NOT APPLE)
     message(FATAL_ERROR "Generating libLLVM-c is only supported on Darwin")
   endif()
 
+  if(NOT LLVM_BUILD_LLVM_DYLIB)
+    message(FATAL_ERROR "Generating libLLVM-c requires LLVM_BUILD_LLVM_C_DYLIB on Darwin")
+  endif()
+
+  # To get the export list for a single llvm library:
+  # nm ${LIB_PATH} | awk "/T _LLVM/ { print $3 }" | sort -u | sed -e "s/^_//g" > ${LIB_PATH}.exports
+
   set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_BINARY_DIR}/libllvm-c.exports)
 
   set(LIB_DIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
@@ -104,3 +114,40 @@
               " -compatibility_version 1 -current_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH} -Wl,-reexport_library ${LIB_PATH}")
 endif()
 
+if(MSVC)
+  # Build the LLVM-C.dll library that exports the C API.
+
+  set(LLVM_LINK_COMPONENTS
+    ${LLVM_DYLIB_COMPONENTS}
+    )
+
+  llvm_map_components_to_libnames(LIB_NAMES ${LLVM_DYLIB_COMPONENTS})
+  list(REMOVE_DUPLICATES LIB_NAMES)
+
+  # The python script needs to know whether symbols are prefixed with underscores or not.
+  if(LLVM_HOST_TRIPLE STREQUAL "i686-pc-win32")
+    set(GEN_UNDERSCORE "--underscore")
+  else()
+    set(GEN_UNDERSCORE "")
+  endif()
+
+  # Get the full name to the libs so the python script understands them.
+  foreach(lib ${LIB_NAMES})
+    list(APPEND FULL_LIB_NAMES ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib/${lib}.lib)
+  endforeach()
+
+  # Generate the exports file dynamically.
+  set(GEN_SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/gen-msvc-exports.py)
+
+  set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/libllvm-c.exports)
+
+  add_custom_command(OUTPUT ${LLVM_EXPORTED_SYMBOL_FILE}
+    COMMAND ${PYTHON_EXECUTABLE} ${GEN_SCRIPT} ${FULL_LIB_NAMES} ${GEN_UNDERSCORE} --nm ${LLVM_TOOLS_BINARY_DIR}/llvm-nm -o ${LLVM_EXPORTED_SYMBOL_FILE}
+    DEPENDS ${LIB_NAMES} llvm-nm
+    COMMENT "Generating export list for LLVM-C"
+    VERBATIM )
+
+  # Finally link the target.
+  add_llvm_library(LLVM-C SHARED ${SOURCES} DEPENDS intrinsics_gen)
+
+endif()
Index: tools/llvm-shlib/gen-msvc-exports.py
===================================================================
--- /dev/null
+++ tools/llvm-shlib/gen-msvc-exports.py
@@ -0,0 +1,106 @@
+#===- gen-msvc-exports.py - Generate C API export file -------*- python -*--===#
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+#===------------------------------------------------------------------------===#
+#
+# Generate an export file from a list of given LIB files. This only exports symbols
+# that start with LLVM, so it only exports the LLVM C API.
+#
+# To have CMake run this, set LLVM_BUILD_LLVM_C_DYLIB to on while
+# building on Windows.
+#
+# To run manually, build LLVM with Visual Studio, use a Command prompt
+# to navigate to the directory with the .lib files (Debug\lib etc). Then run
+#     python C:\Path\To\gen-msvc-exports.py --nm ..\bin\llvm-nm.exe LLVM*.lib
+#
+# If you're generating a 32 bit DLL, use the `--underscore` flag.
+# If you want to use a different `llvm-nm` executable, pass the path
+# with the `--nm` flag.
+#
+# You can use the --output flag to set the name of the export file.
+#
+#===------------------------------------------------------------------------===#
+from tempfile import mkstemp
+from contextlib import contextmanager
+from subprocess import check_call
+import argparse
+import os
+import re
+
+
+_UNDERSCORE_REGEX = {
+    False: re.compile(r"^\w+\s+T\s+(LLVM.*)$"),
+    True:  re.compile(r"^\w+\s+T\s+_(LLVM.*)$")
+}
+
+
+@contextmanager
+def removing(path):
+    try:
+        yield path
+    finally:
+        os.unlink(path)
+
+
+def touch_tempfile(*args, **kwargs):
+    fd, name = mkstemp(*args, **kwargs)
+    os.close(fd)
+    return name
+
+
+def gen_llvm_c_export(output, underscore, libs, nm):
+    """Generate the export file for the LLVM-C DLL.
+
+    Run `nm` for each lib in `libs`, and output an export file
+    to `output`. If `underscore` is true, symbols will
+    be assumed to be prefixed with an underscore.
+    """
+    with removing(touch_tempfile(prefix='dumpout', suffix='.txt')) as dumpout:
+
+        # Get the right regex.
+        p = _UNDERSCORE_REGEX[underscore]
+
+        with open(output, 'w+t') as output_f:
+
+            # For each lib get the LLVM* functions it exports.
+            for lib in libs:
+                # Call dumpbin.
+                with open(dumpout, 'w+t') as dumpout_f:
+                    check_call([nm, '-g', lib], stdout=dumpout_f)
+
+                # Get the matching lines.
+                with open(dumpout) as dumpbin:
+                    for line in dumpbin:
+                        m = p.match(line)
+                        if m is not None:
+                            output_f.write(m.group(1) + '\n')
+
+
+def main():
+    parser = argparse.ArgumentParser('gen-msvc-exports')
+
+    parser.add_argument(
+        '-o', '--output', help='output filename', default='LLVM-C.exports'
+    )
+    parser.add_argument('-u', '--underscore',
+        help='labels are prefixed with an underscore (use for 32 bit DLLs)',
+        action='store_true'
+    )
+    parser.add_argument(
+        '--nm', help='path to the llvm-nm executable', default='llvm-nm'
+    )
+    parser.add_argument(
+        'libs', metavar='LIBS', nargs='+', help='list of libraries to generate export from'
+    )
+
+    ns = parser.parse_args()
+
+    gen_llvm_c_export(ns.output, ns.underscore, ns.libs, ns.nm)
+
+
+if __name__ == '__main__':
+    main()