diff --git a/Makefile b/Makefile
index fe227f4..4168519 100644
--- a/Makefile
+++ b/Makefile
@@ -55,7 +55,7 @@ build/compiler-rt.BUILT: build/llvm.BUILT
 		-DCOMPILER_RT_INCLUDE_TESTS=OFF \
 		-DCOMPILER_RT_ENABLE_IOS=OFF \
 		-DCOMPILER_RT_DEFAULT_TARGET_ONLY=On \
-		-DWASM_SDK_PREFIX=$(PREFIX) \
+		-DWASI_SDK_PREFIX=$(PREFIX) \
 		-DCMAKE_C_FLAGS="-O1 $(DEBUG_PREFIX_MAP)" \
 		-DLLVM_CONFIG_PATH=$(ROOT_DIR)/build/llvm/bin/llvm-config \
 		-DCOMPILER_RT_OS_DIR=wasi \
@@ -81,7 +81,7 @@ build/libcxx.BUILT: build/llvm.BUILT build/compiler-rt.BUILT build/reference-sys
 		-DLIBCXX_CXX_ABI_INCLUDE_PATHS=$(ROOT_DIR)/src/llvm-project/libcxxabi/include \
 		-DLIBCXX_HAS_MUSL_LIBC:BOOL=ON \
 		-DLIBCXX_ABI_VERSION=2 \
-		-DWASM_SDK_PREFIX=$(PREFIX) \
+		-DWASI_SDK_PREFIX=$(PREFIX) \
 		-DCMAKE_C_FLAGS="$(DEBUG_PREFIX_MAP)" \
 		-DCMAKE_CXX_FLAGS="$(DEBUG_PREFIX_MAP)" \
 		--debug-trycompile \
@@ -107,7 +107,7 @@ build/libcxxabi.BUILT: build/libcxx.BUILT build/llvm.BUILT
 		-DLIBCXXABI_LIBCXX_INCLUDES=$(PREFIX)/share/sysroot/include/c++/v1 \
 		-DLLVM_CONFIG_PATH=$(ROOT_DIR)/build/llvm/bin/llvm-config \
 		-DCMAKE_TOOLCHAIN_FILE=$(ROOT_DIR)/wasi-sdk.cmake \
-		-DWASM_SDK_PREFIX=$(PREFIX) \
+		-DWASI_SDK_PREFIX=$(PREFIX) \
 		-DCMAKE_C_FLAGS="$(DEBUG_PREFIX_MAP)" \
 		-DCMAKE_CXX_FLAGS="$(DEBUG_PREFIX_MAP)" \
 		-DUNIX:BOOL=ON \
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..3d30624
--- /dev/null
+++ b/README.md
@@ -0,0 +1,22 @@
+# WASI SDK
+
+## Quick Start
+
+[Download SDK packages here.](https://github.com/CraneStation/wasi-sdk/releases)
+
+## About this repository
+
+This repository contains no compiler or library code itself; it uses
+git submodules to pull in the upstream Clang and LLVM tree, as well as the
+WASI reference-sysroot tree.
+
+The Sysroot portion of this SDK is the
+[WASI reference-sysroot](https://github.com/CraneStation/reference-sysroot).
+
+Upstream Clang and LLVM 8.0 can compile for WASI out of the box, and WebAssembly
+support is included in them by default. So, all that's done here is to provide
+builds configured to set the default target and sysroot for convenience.
+
+One could also use a standard Clang 8.0, build a sysroot from the sources
+mentioned above, and compile with
+"--target=wasm32-unknown-wasi --sysroot=/path/to/sysroot".
diff --git a/wasi-sdk.cmake b/wasi-sdk.cmake
index 6ec193b..2153185 100644
--- a/wasi-sdk.cmake
+++ b/wasi-sdk.cmake
@@ -8,18 +8,18 @@ set(CMAKE_SYSTEM_VERSION 1)
 set(CMAKE_SYSTEM_PROCESSOR wasm32)
 set(triple wasm32-unknown-wasi)
 
-set(CMAKE_C_COMPILER ${WASM_SDK_PREFIX}/bin/clang)
-set(CMAKE_CXX_COMPILER ${WASM_SDK_PREFIX}/bin/clang++)
-set(CMAKE_AR ${WASM_SDK_PREFIX}/bin/llvm-ar CACHE STRING "wasi-sdk build")
-set(CMAKE_RANLIB ${WASM_SDK_PREFIX}/bin/llvm-ranlib CACHE STRING "wasi-sdk build")
+set(CMAKE_C_COMPILER ${WASI_SDK_PREFIX}/bin/clang)
+set(CMAKE_CXX_COMPILER ${WASI_SDK_PREFIX}/bin/clang++)
+set(CMAKE_AR ${WASI_SDK_PREFIX}/bin/llvm-ar CACHE STRING "wasi-sdk build")
+set(CMAKE_RANLIB ${WASI_SDK_PREFIX}/bin/llvm-ranlib CACHE STRING "wasi-sdk build")
 set(CMAKE_C_COMPILER_TARGET ${triple} CACHE STRING "wasi-sdk build")
 set(CMAKE_CXX_COMPILER_TARGET ${triple} CACHE STRING "wasi-sdk build")
 set(CMAKE_C_FLAGS "-v" CACHE STRING "wasi-sdk build")
 set(CMAKE_CXX_FLAGS "-v -std=c++11" CACHE STRING "wasi-sdk build")
 set(CMAKE_EXE_LINKER_FLAGS "-Wl,--no-threads" CACHE STRING "wasi-sdk build")
 
-set(CMAKE_SYSROOT ${WASM_SDK_PREFIX}/share/sysroot CACHE STRING "wasi-sdk build")
-set(CMAKE_STAGING_PREFIX ${WASM_SDK_PREFIX}/share/sysroot CACHE STRING "wasi-sdk build")
+set(CMAKE_SYSROOT ${WASI_SDK_PREFIX}/share/sysroot CACHE STRING "wasi-sdk build")
+set(CMAKE_STAGING_PREFIX ${WASI_SDK_PREFIX}/share/sysroot CACHE STRING "wasi-sdk build")
 
 # Don't look in the sysroot for executables to run during the build
 set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)