diff --git a/.gitignore b/.gitignore
index 6ee7af9f4..f7a687c89 100644
--- a/.gitignore
+++ b/.gitignore
@@ -53,6 +53,7 @@ libs
 objs
 
 # Build outputs (TODO build to a subdir so we can exclude that instead)
+/.simdjson-user-CMakeCache.txt
 /allparserscheckfile
 /allparsingcompetition
 /basictests
@@ -124,10 +125,10 @@ objs
 /stringparsingcheck
 /submodules
 /ujdecode.o
-/amalgamation_demo.cpp
+/amalgamate_demo.cpp
 /simdjson.cpp
 /simdjson.h
-/singleheader/amalgamation_demo
+/singleheader/amalgamate_demo
 /singleheader/demo
 /tests/allparserscheckfile
 /tests/basictests
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6b5826f22..f8c9d070f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,6 +17,7 @@ set(PROJECT_VERSION_MINOR 3)
 set(PROJECT_VERSION_PATCH 1)
 set(SIMDJSON_LIB_VERSION "0.3.1" CACHE STRING "simdjson library version")
 set(SIMDJSON_LIB_SOVERSION "1" CACHE STRING "simdjson library soversion")
+set(SIMDJSON_GITHUB_REPOSITORY https://github.com/simdjson/simdjson)
 
 if(MSVC)
   option(SIMDJSON_BUILD_STATIC "Build a static library" ON) # turning it on disables the production of a dynamic library
@@ -120,6 +121,23 @@ endfunction()
 
 export_private_library(simdjson-flags)
 
+#
+# ${SIMDJSON_USER_CMAKECACHE} contains the *user-specified* simdjson options so you can call cmake on
+# another branch or repository with the same options.
+#
+# Not supported on Windows at present, because the only thing that uses it is checkperf, which we
+# don't run on Windows.
+#
+if (NOT MSVC)
+  set(SIMDJSON_USER_CMAKECACHE ${CMAKE_CURRENT_BINARY_DIR}/.simdjson-user-CMakeCache.txt)
+  add_custom_command(
+    OUTPUT ${SIMDJSON_USER_CMAKECACHE}
+    COMMAND bash -c "grep SIMDJSON_ ${PROJECT_BINARY_DIR}/CMakeCache.txt | grep -v SIMDJSON_LIB_ > ${SIMDJSON_USER_CMAKECACHE}"
+    VERBATIM # Makes it not do weird escaping with the command
+  )
+  add_custom_target(simdjson-user-cmakecache ALL DEPENDS ${SIMDJSON_USER_CMAKECACHE})
+endif()
+
 #
 # Create the top level simdjson library (must be done at this level to use both src/ and include/
 # directories) and tools
diff --git a/benchmark/CMakeLists.txt b/benchmark/CMakeLists.txt
index 543a56520..647eb4a3e 100644
--- a/benchmark/CMakeLists.txt
+++ b/benchmark/CMakeLists.txt
@@ -41,6 +41,7 @@ if (NOT MSVC)
       CHECKPERF_REPOSITORY=https://github.com/simdjson/simdjson
       CHECKPERF_BRANCH=master
       CHECKPERF_DIR=${CMAKE_CURRENT_BINARY_DIR}/simdjson-master
+      CHECKPERF_CMAKECACHE=${SIMDJSON_USER_CMAKECACHE}
       bash ${CMAKE_CURRENT_SOURCE_DIR}/checkperf.sh ${PROJECT_SOURCE_DIR}/jsonexamples/twitter.json)
-  set_property(TEST checkperf APPEND PROPERTY DEPENDS parse perfdiff)
-endif()
\ No newline at end of file
+  set_property(TEST checkperf APPEND PROPERTY DEPENDS parse perfdiff ${SIMDJSON_USER_CMAKECACHE})
+endif()
diff --git a/benchmark/checkperf.sh b/benchmark/checkperf.sh
index f133c063e..0099d82bb 100644
--- a/benchmark/checkperf.sh
+++ b/benchmark/checkperf.sh
@@ -2,6 +2,8 @@
 
 set -ex
 
+set | grep CHECKPERF
+
 if [ -z "$CHECKPERF_REPOSITORY" ]; then CHECKPERF_REPOSITORY=.; fi
 
 # Arguments: perfdiff.sh <branch> <test json files>
@@ -29,10 +31,18 @@ else
 fi
 
 echo "Building $CHECKPERF_DIR/parse ..."
-make parse
+if [ -n "$CHECKPERF_CMAKECACHE" ]; then
+  cp $CHECKPERF_CMAKECACHE $CHECKPERF_DIR/CMakeCache.txt
+  cmake -DSIMDJSON_GOOGLE_BENCHMARKS=OFF -DSIMDJSON_COMPETITION=OFF .
+  make parse
+  REFERENCE_PARSE=$CHECKPERF_DIR/benchmark/parse
+else
+  make parse
+  REFERENCE_PARSE=$CHECKPERF_DIR/parse
+fi
 popd
 
 # Run them and diff performance
 echo "Running perfdiff:"
-echo ./perfdiff \"./parse -t $CHECKPERF_ARGS\" \"$CHECKPERF_DIR/parse -t $CHECKPERF_ARGS\"
-./perfdiff "./parse -t $CHECKPERF_ARGS" "$CHECKPERF_DIR/parse -t $CHECKPERF_ARGS"
+echo ./perfdiff \"./parse -t $CHECKPERF_ARGS\" \"$REFERENCE_PARSE -t $CHECKPERF_ARGS\"
+./perfdiff "./parse -t $CHECKPERF_ARGS" "$REFERENCE_PARSE -t $CHECKPERF_ARGS"