Index: llvm/cmake/modules/Findzstd.cmake
===================================================================
--- /dev/null
+++ llvm/cmake/modules/Findzstd.cmake
@@ -0,0 +1,47 @@
+# Try to find the zstd library
+#
+# If successful, the following variables will be defined:
+# zstd_INCLUDE_DIR
+# zstd_LIBRARY
+# zstd_STATIC_LIBRARY
+# zstd_FOUND
+#
+# Additionally, the following import targets will be defined:
+# zstd::libzstd_shared
+# zstd::libzstd_static
+
+find_package(PkgConfig QUIET)
+pkg_check_modules(PC_LIBZSTD QUIET libzstd)
+
+find_path(zstd_INCLUDE_DIR NAMES zstd.h HINTS ${PC_LIBZSTD_INCLUDE_DIRS})
+find_library(zstd_LIBRARY NAMES zstd HINTS ${PC_LIBZSTD_LIBRARY_DIRS})
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(
+  zstd DEFAULT_MSG
+  zstd_LIBRARY zstd_INCLUDE_DIR)
+
+if(zstd_FOUND)
+  if(zstd_LIBRARY MATCHES "\\${CMAKE_SHARED_LIBRARY_SUFFIX}$" AND
+     NOT TARGET zstd::libzstd_shared)
+    add_library(zstd::libzstd_shared UNKNOWN IMPORTED)
+    set_target_properties(zstd::libzstd_shared PROPERTIES
+      INTERFACE_INCLUDE_DIRECTORIES "${zstd_INCLUDE_DIR}"
+      IMPORTED_LOCATION "${zstd_LIBRARY}")
+
+    # Try to find the static library in addition to the shared library.
+    find_library(zstd_STATIC_LIBRARY
+      NAMES "${CMAKE_STATIC_LIBRARY_PREFIX}zstd${CMAKE_STATIC_LIBRARY_SUFFIX}")
+  else()
+    set(zstd_STATIC_LIBRARY "${zstd_LIBRARY}")
+  endif()
+  if(zstd_STATIC_LIBRARY MATCHES "\\${CMAKE_STATIC_LIBRARY_SUFFIX}$" AND
+     NOT TARGET zstd::libzstd_static)
+    add_library(zstd::libzstd_static UNKNOWN IMPORTED)
+    set_target_properties(zstd::libzstd_static PROPERTIES
+      INTERFACE_INCLUDE_DIRECTORIES "${zstd_INCLUDE_DIR}"
+      IMPORTED_LOCATION "${zstd_STATIC_LIBRARY}")
+  endif()
+endif()
+
+mark_as_advanced(zstd_INCLUDE_DIR zstd_LIBRARY zstd_STATIC_LIBRARY)