diff --git a/.gitignore b/.gitignore
index dd604e85a..4a929ce91 100644
--- a/.gitignore
+++ b/.gitignore
@@ -158,3 +158,7 @@ infer/src/.project
 /infer/src/istd/jbuild
 /infer/src/scripts/jbuild
 /infer/src/jbuild-workspace
+
+# generated when looking for dead code
+/infer/src/deadcode/.depend
+/infer/src/deadcode/jbuild
diff --git a/infer/src/Makefile b/infer/src/Makefile
index cefed909d..c7e7f1a72 100644
--- a/infer/src/Makefile
+++ b/infer/src/Makefile
@@ -95,7 +95,7 @@ all: infer
 
 GENERATED_FROM_AUTOCONF = jbuild.common jbuild-workspace base/Version.ml
 
-GENERATED_JBUILDS = jbuild atd/jbuild istd/jbuild scripts/jbuild
+GENERATED_JBUILDS = jbuild atd/jbuild deadcode/jbuild istd/jbuild scripts/jbuild
 
 SRC_BUILD_COMMON = $(GENERATED_FROM_AUTOCONF) $(GENERATED_JBUILDS) $(OCAML_SOURCES)
 ifeq ($(BUILD_C_ANALYZERS),yes)
@@ -159,7 +159,7 @@ roots += $(INFER_CREATE_TRACEVIEW_LINKS_MODULE)
 endif
 clusters:=base clang java IR
 
-ml_src_files:=$(shell find . -regex '\./[a-zA-Z].*\.ml\(i\)*')
+ml_src_files:=$(shell find . -not -path "./*stubs*" -regex '\./[a-zA-Z].*\.ml\(i\)*')
 inc_flags:=$(foreach dir,$(shell find . -type d),-I $(dir))
 root_flags:=$(foreach root,$(roots),-r $(root))
 cluster_flags:=$(foreach cluster,$(clusters),-c $(cluster))
@@ -265,11 +265,13 @@ $(GENERATED_JBUILDS): jbuild.common
 
 jbuild: jbuild.in
 atd/jbuild: atd/jbuild.in
+deadcode/jbuild: deadcode/jbuild.in
 istd/jbuild: istd/jbuild.in
 scripts/jbuild: scripts/jbuild.in
 
 .PHONY: clean
 clean:
+	$(MAKE) -C deadcode clean
 	$(REMOVE) $(INFER_TARGET)
 	$(REMOVE) toplevel.mlpack
 	$(REMOVE_DIR) $(BUILD_DIR)
diff --git a/infer/src/deadcode/Makefile b/infer/src/deadcode/Makefile
new file mode 100644
index 000000000..d5e807226
--- /dev/null
+++ b/infer/src/deadcode/Makefile
@@ -0,0 +1,135 @@
+# Copyright (c) 2018 - present Facebook, Inc.
+# All rights reserved.
+#
+# This source code is licensed under the BSD style license found in the
+# LICENSE file in the root directory of this source tree. An additional grant
+# of patent rights can be found in the PATENTS file in the same directory.
+
+# Dead code detection: type `make` in this directory.
+#
+# OCaml will not detect dead code as soon as it gets exported in a .mli file. But, it will detect
+# dead code in inlined modules, even if they have a signature. This suggests the following idea,
+# which is basically what happens here:
+#
+# 1. Put all of the infer source code into a single .ml file with an empty .mli. Each file is put
+#   inside its own inline module, with its original signature included too to avoid ambiguities in
+#   case of locally opened modules (which may shadow more values than intended otherwise).
+# 2. Add preprocessor instructions so that OCaml warnings are shown in the original files.
+# 3. Suppress warnings in source code copied from generated files (atdgen, lexers, and parsers).
+# 3. Run the OCaml compiler.
+# 4. Kill detected dead code; repeat until dry.
+#
+# Infer is first compiled so that atdgen, ocamllex, and menhir generate the appropriate files. The
+# ocamllex and menhir files are generated inside ../_build by jbuilder, and copied here by this
+# Makefile.
+#
+# ocamldepend is used to `cat` the source files in the right order into all_infer_in_one_file.ml.
+#
+# Beware that this is mostly a terrible hack.
+
+ROOT_DIR = ../../..
+include $(ROOT_DIR)/Makefile.config
+
+default: detect_dead_code
+
+ml_src_files_from_mlly:=$(shell find .. -not -path "../*stubs*" -regex '\.\./[a-zA-Z].*\.ml\(l\|y\)')
+
+ml_src_files:=$(shell cd .. && find . -not -path "./*stubs*" -regex '\./[a-zA-Z].*\.ml\(i\)*')
+
+ml_src_files_without_mli:=$(shell cd .. && for i in */*.ml */*/*.ml; do [ -f $${i}i ] || echo $$i; done)
+
+.PHONY: depend
+depend:
+	cd .. && \
+	ocamldep -native \
+	  -I IR -I absint -I atd -I backend -I base -I bufferoverrun -I checkers \
+	  -I clang -I concurrency -I eradicate -I facebook -I integration -I istd \
+	  -I java -I labs -I python -I quandary -I unit -I unit/clang -I deadcode \
+	   $(ml_src_files) > deadcode/.depend
+
+%.cmi:
+#	deal with the .ml *and* the .mli at the same time: when all the modules are inlined in one
+#	file, you need the module value to be defined before you can refer to it, even in
+#	signatures. Because of this, the order given by ocamldep is not enough to avoid "Unbound
+#	module MyModule" errors in the case of signatures referring to other modules.
+	$(QUIET)echo "(* START OF SIGNATURE $*.mli *)" >> all_infer_in_one_file.ml
+#	put too many spaces in general but you never know what the contents of the file is;
+#	sometimes spaces will be needed
+	$(QUIET)echo "  module type " >> all_infer_in_one_file.ml
+#	suppress some warnings for generated code
+	$(QUIET)if [[ $@ =~ (atd|deadcode)/ ]]; then echo '  [@warning "-27-32-34-35-39"] ' >> all_infer_in_one_file.ml; fi
+#	compute module name from file name: capitalize first letter
+	$(QUIET)echo $(shell basename $*) | sed -e "s/\b\(.\)/  \u\1/g" >> all_infer_in_one_file.ml
+	$(QUIET)echo "  = sig " >> all_infer_in_one_file.ml
+#	pre-processor directive to get errors in the original files and not in all_infer_in_one_file.ml
+	$(QUIET)echo '# 1 "$*.mli"' >> all_infer_in_one_file.ml
+	cat ../$*.mli >> all_infer_in_one_file.ml
+	$(QUIET)echo "  end " >> all_infer_in_one_file.ml
+	$(QUIET)echo "(* END OF SIGNATURE $*.mli *)" >> all_infer_in_one_file.ml
+	$(QUIET)echo >> all_infer_in_one_file.ml
+#	lots of duplication from above, sorry
+	$(QUIET)echo "(* START OF MODULE $*.ml *)" >> all_infer_in_one_file.ml
+	$(QUIET)echo "  module " >> all_infer_in_one_file.ml
+	$(QUIET)if [[ $@ =~ (atd|deadcode)/ ]]; then echo '  [@warning "-27-32-34-35-39"] ' >> all_infer_in_one_file.ml; fi
+	$(QUIET)echo $(shell basename $*) | sed -e "s/\b\(.\)/  \u\1/g" >> all_infer_in_one_file.ml
+	$(QUIET)echo "  : " >> all_infer_in_one_file.ml
+	$(QUIET)echo $(shell basename $*) | sed -e "s/\b\(.\)/  \u\1/g" >> all_infer_in_one_file.ml
+	$(QUIET)echo "  = struct " >> all_infer_in_one_file.ml
+	$(QUIET)echo '# 1 "$*.ml"' >> all_infer_in_one_file.ml
+	cat ../$*.ml >> all_infer_in_one_file.ml
+	$(QUIET)echo "  end " >> all_infer_in_one_file.ml
+	$(QUIET)echo "(* END OF MODULE $*.ml *)" >> all_infer_in_one_file.ml
+	$(QUIET)echo >> all_infer_in_one_file.ml
+
+$(ml_src_files_without_mli:.ml=.cmx):
+#	again mostly duplicated from above
+	$(QUIET)echo "(* START OF MODULE $(@) *)" >> all_infer_in_one_file.ml
+	$(QUIET)echo "  module " >> all_infer_in_one_file.ml
+	$(QUIET)if [[ $@ =~ (atd|deadcode)/ ]]; then echo '  [@warning "-27-32-34-35-39"] ' >> all_infer_in_one_file.ml; fi
+	$(QUIET)echo $(shell basename $@ .cmx) | sed -e "s/\b\(.\)/  \u\1/g" >> all_infer_in_one_file.ml
+	$(QUIET)echo "  = struct " >> all_infer_in_one_file.ml
+	$(QUIET)echo "# 1 \"$$(echo $@ | sed -e 's/\.cmx$$/.ml/')\"" >> all_infer_in_one_file.ml
+	cat ../$$(echo $@ | sed -e "s/\.cmx$$/.ml/") >> all_infer_in_one_file.ml
+	$(QUIET)echo "  end " >> all_infer_in_one_file.ml
+	$(QUIET)echo "(* END OF MODULE $@ *)" >> all_infer_in_one_file.ml
+	$(QUIET)echo >> all_infer_in_one_file.ml
+
+-include .depend
+
+.PHONY: all_infer_in_one_file.ml
+all_infer_in_one_file.ml: backend/infer.cmx unit/inferunit.cmx facebook/InferCreateTraceViewLinks.cmx
+	$(QUIET)echo "see results in all_infer_in_one_file.ml"
+
+.PHONY: detect_dead_code
+detect_dead_code:
+	$(MAKE) clean
+#	needed to get jbuild generated, and the generated code for the lexers and parsers in ../_build
+	$(MAKE) -C .. byte
+#	copy generated source files from ../_build
+	for file in $(ml_src_files_from_mlly); do \
+	  set +e; \
+	  [ -f "../_build/default/$$(basename $$file .mly).ml" ] && \
+	    $(COPY) ../_build/default/$$(basename $$file .mly).ml .; \
+	  [ -f "../_build/default/$$(basename $$file .mly).mli" ] && \
+	    $(COPY) ../_build/default/$$(basename $$file .mly).mli .; \
+	  [ -f "../_build/default/$$(basename $$file .mll).ml" ] && \
+	    $(COPY) ../_build/default/$$(basename $$file .mll).ml .; \
+	  [ -f "../_build/default/$$(basename $$file .mll).mli" ] && \
+	    $(COPY) ../_build/default/$$(basename $$file .mll).mli .; \
+	  set -e; \
+	done
+	$(REMOVE) all_infer_in_one_file.ml
+	$(MAKE) depend
+#	Need to be sequential to avoid getting a garbled file. Need to re-include .depend as it may
+#	have changed, so run another `make`.
+	$(MAKE) -j 1 all_infer_in_one_file.ml
+#	build and get dead code warnings
+	jbuilder build ../_build/default/deadcode/all_infer_in_one_file.bc
+#	be paranoid about cleaning because we do not want to include infer_in_one_file into infer by
+#	accident and I don't know enough jbuilder to be positive that it won't happen
+	$(MAKE) clean
+
+.PHONY: clean
+clean:
+	$(REMOVE) .depend *.ml *.mli jbuild
+	touch all_infer_in_one_file.mli all_infer_in_one_file.ml
diff --git a/infer/src/deadcode/all_infer_in_one_file.ml b/infer/src/deadcode/all_infer_in_one_file.ml
new file mode 100644
index 000000000..e69de29bb
diff --git a/infer/src/deadcode/all_infer_in_one_file.mli b/infer/src/deadcode/all_infer_in_one_file.mli
new file mode 100644
index 000000000..e69de29bb
diff --git a/infer/src/deadcode/jbuild.in b/infer/src/deadcode/jbuild.in
new file mode 100644
index 000000000..a2e5dff37
--- /dev/null
+++ b/infer/src/deadcode/jbuild.in
@@ -0,0 +1,18 @@
+(* -*- tuareg -*- *)
+(* NOTE: prepend jbuild.common to this file! *)
+
+;; Format.sprintf
+     {|
+(executable
+ ((name all_infer_in_one_file)
+  (flags (%s))
+  (ocamlopt_flags (%s))
+  (libraries (%s))
+  (modules (All_infer_in_one_file))
+  (preprocess (pps (ppx_compare ppx_sexp_conv -no-check)))
+ ))
+|}
+     (String.concat " " common_cflags)
+     (String.concat " " common_optflags)
+     (String.concat " " common_libraries)
+   |> Jbuild_plugin.V1.send
diff --git a/scripts/dead_code_detection.sh b/scripts/dead_code_detection.sh
new file mode 100755
index 000000000..5e2829ca1
--- /dev/null
+++ b/scripts/dead_code_detection.sh
@@ -0,0 +1,19 @@
+#!/bin/bash
+
+# Copyright (c) 2018 - present Facebook, Inc.
+# All rights reserved.
+#
+# This source code is licensed under the BSD style license found in the
+# LICENSE file in the root directory of this source tree. An additional grant
+# of patent rights can be found in the PATENTS file in the same directory.
+
+
+# Dead code detection for infer's source code. See comments in infer/src/deadcode/Makefile.
+
+set -e
+set -o pipefail
+set -u
+
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+make -C "$SCRIPT_DIR"/../infer/src/deadcode