diff --git a/.gitignore b/.gitignore
index f59a91d54..d7b3bc8a1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -78,6 +78,7 @@ messages.pot
 /lexicon_filter
 /toc.txt
 /version
+fish-build-version-witness.txt
 
 # File names that can appear below the project root that represent artifacts
 # from building and testing.
@@ -101,4 +102,5 @@ xcuserdata/
 *.moved-aside
 *.xccheckout
 *.xcscmblueprin
+.vscode
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e31dbdd86..2ffb17956 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -55,17 +55,6 @@ SET(FISH_SRCS
 # Header files are just globbed.
 FILE(GLOB FISH_HEADERS src/*.h)
 
-# Set up the version target.
-# This creates the file FISH-BUILD-VERSION-FILE which is only modified if necessary.
-ADD_CUSTOM_COMMAND(OUTPUT "FISH-BUILD-VERSION-FILE"
-                   DEPENDS CHECK-FISH-BUILD-VERSION-FILE)
-
-ADD_CUSTOM_TARGET("CHECK-FISH-BUILD-VERSION-FILE"
-                  COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/build_tools/git_version_gen.sh)
-
-SET(FBVF "FISH-BUILD-VERSION-FILE")
-
-
 # Set up config.h
 INCLUDE(cmake/ConfigureChecks.cmake)
 INCLUDE(cmake/gettext.cmake)
@@ -76,7 +65,6 @@ INCLUDE_DIRECTORIES(${CMAKE_CURRENT_BINARY_DIR})
 # Set up standard directories.
 INCLUDE(GNUInstallDirs)
 ADD_DEFINITIONS(-D_UNICODE=1
-                -DFISH_BUILD_VERSION="${FISH_BUILD_VERSION}"
                 -DLOCALEDIR="${CMAKE_INSTALL_FULL_LOCALEDIR}"
                 -DPREFIX=L"${CMAKE_INSTALL_PREFIX}"
                 -DDATADIR=L"${CMAKE_INSTALL_FULL_DATADIR}"
@@ -84,6 +72,16 @@ ADD_DEFINITIONS(-D_UNICODE=1
                 -DBINDIR=L"${CMAKE_INSTALL_FULL_BINDIR}"
                 -DDOCDIR=L"${CMAKE_INSTALL_FULL_DOCDIR}")
 
+# Set up the machinery around FISH-BUILD-VERSION-FILE
+# This defines the FBVF variable.
+INCLUDE(Version)
+
+# Teach fish_version.o to rebuild when FBVF changes.
+# The standard C++ include detection machinery misses this.
+SET_SOURCE_FILES_PROPERTIES(src/fish_version.cpp
+                            PROPERTIES OBJECT_DEPENDS
+                            ${CMAKE_CURRENT_BINARY_DIR}/${FBVF})
+
 # Set up PCRE2
 INCLUDE(cmake/PCRE2.cmake)
 
diff --git a/build_tools/git_version_gen.sh b/build_tools/git_version_gen.sh
index cb208f76c..bbf780b49 100755
--- a/build_tools/git_version_gen.sh
+++ b/build_tools/git_version_gen.sh
@@ -1,14 +1,11 @@
-#!/bin/sh
+#!/bin/bash
 # Originally from the git sources (GIT-VERSION-GEN)
 # Presumably (C) Junio C Hamano <junkio@cox.net>
 # Reused under GPL v2.0
 # Modified for fish by David Adam <zanchey@ucc.gu.uwa.edu.au>
 
-# Obtain directory containing this script in POSIX-compatible manner
-# See https://stackoverflow.com/a/43919044/17027 (public domain)
-a="/$0"; a="${a%/*}"; a="${a:-.}"; a="${a#/}/"; BASEDIR=$(cd "$a"; pwd)
-# Find the fish git directory as two levels up from this directory.
-GIT_DIR=$(dirname "$a")
+# Find the fish git directory as two levels up from script directory.
+GIT_DIR="$( cd "$( dirname $( dirname "${BASH_SOURCE[0]}" ) )" && pwd )"
 
 FBVF=FISH-BUILD-VERSION-FILE
 DEF_VER=unknown
@@ -24,11 +21,21 @@ fi
 
 if test -r $FBVF
 then
-	VC=$(sed -e 's/^FISH_BUILD_VERSION=//' <$FBVF)
+	VC=$(grep -v '^#' $FBVF | tr -d '"' | sed -e 's/^FISH_BUILD_VERSION=//')
 else
 	VC=unset
 fi
+
+# Output the FBVF
+# Note that we are super-double sneaky: we produce a file that is valid bash
+# and valid C++, so it may be included from either. Also it may have leading
+# hashes filtered out with grep to get a version of the form (for example):
+#   FISH_BUILD_VERSION=2.7.1-620-g94c9f5c2
 test "$VN" = "$VC" || {
 	echo >&2 "FISH_BUILD_VERSION=$VN"
-	echo "FISH_BUILD_VERSION=$VN" >$FBVF
+	echo "FISH_BUILD_VERSION=\"$VN\"" >$FBVF
 }
+
+# Output the fish-build-version-witness.txt
+# See https://cmake.org/cmake/help/v3.4/policy/CMP0058.html
+date +%s > fish-build-version-witness.txt
diff --git a/cmake/Docs.cmake b/cmake/Docs.cmake
index 1ca360166..76a0c89b2 100644
--- a/cmake/Docs.cmake
+++ b/cmake/Docs.cmake
@@ -70,7 +70,7 @@ ADD_CUSTOM_COMMAND(OUTPUT doc.h
 # Note we would like to add doc_src/index.hdr.in as a dependency but CMake replaces this with
 # doc_src/index.hdr; CMake bug?
 ADD_CUSTOM_COMMAND(OUTPUT toc.txt
-                   COMMAND env `cat ${FBVF}` ${CMAKE_CURRENT_SOURCE_DIR}/build_tools/build_toc_txt.sh
+                   COMMAND env `cat ${FBVF} | tr -d '\"'` ${CMAKE_CURRENT_SOURCE_DIR}/build_tools/build_toc_txt.sh
                            doc_src/index.hdr.in ${HDR_FILES_NO_INDEX}
                            > ${CMAKE_CURRENT_BINARY_DIR}/toc.txt
                    DEPENDS ${FBVF} ${HDR_FILES_NO_INDEX})
@@ -95,7 +95,7 @@ ADD_CUSTOM_TARGET(doc
                   DEPENDS ${FBVF} Doxyfile.user ${DOC_SRC_FILES} doc.h ${HDR_FILES} lexicon_filter)
 
 ADD_CUSTOM_COMMAND(OUTPUT share/man/
-                   COMMAND env `cat ${FBVF}`
+                   COMMAND env `cat ${FBVF} | tr -d '\"' `
                            INPUT_FILTER=lexicon_filter ${CMAKE_CURRENT_SOURCE_DIR}/build_tools/build_documentation.sh ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.help doc_src ./share
                    DEPENDS ${FBVF} ${HELP_SRC} ${CMAKE_CURRENT_BINARY_DIR}/lexicon_filter)
 
diff --git a/cmake/Install.cmake b/cmake/Install.cmake
index 37b4c3ce7..18a32e104 100644
--- a/cmake/Install.cmake
+++ b/cmake/Install.cmake
@@ -111,7 +111,7 @@ FISH_CREATE_DIRS(${rel_datadir}/pkgconfig ${extra_completionsdir}
 # $v $(INSTALL) -m 644 fish.pc $(DESTDIR)$(datadir)/pkgconfig
 CONFIGURE_FILE(fish.pc.in fish.pc.noversion)
 ADD_CUSTOM_COMMAND(OUTPUT fish.pc
-  COMMAND awk -v `cat ${FBVF}` '/^Version:/ {$$0=$$0 FISH_BUILD_VERSION} 1' fish.pc.noversion  > fish.pc
+  COMMAND awk -v `cat ${FBVF} | tr -d '\"'` '/^Version:/ {$$0=$$0 FISH_BUILD_VERSION} 1' fish.pc.noversion  > fish.pc
   WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
   DEPENDS ${FBVF} ${CMAKE_CURRENT_BINARY_DIR}/fish.pc.noversion)
 
diff --git a/cmake/Version.cmake b/cmake/Version.cmake
new file mode 100644
index 000000000..446c134eb
--- /dev/null
+++ b/cmake/Version.cmake
@@ -0,0 +1,51 @@
+# This file adds commands to manage the FISH-BUILD-VERSION-FILE (hereafter
+# FBVF). This file exists in the build directory and is used to populate the
+# documentation and also the version string in fish_version.o (printed with
+# `echo $version` and also fish --version). The essential idea is that we are
+# going to invoke git_version_gen.sh, which will update the
+# FISH-BUILD-VERSION-FILE only if it needs to change; this is what makes
+# incremental rebuilds fast.
+#
+# This code is delicate, with the chief subtlety revolving around Ninja. A
+# natural and naive approach would tell the generated build system that FBVF is
+# a dependency of fish_version.o, and that git_version_gen.sh updates it. Make
+# will then invoke the script, check the timestamp on fish_version.o and FBVF,
+# see that FBVF is earlier, and then not rebuild fish_version.o. Ninja,
+# however, decides what to build up-front and will unconditionally rebuild
+# fish_version.o.
+#
+# To avoid this with Ninja, we want to hook into its 'restat' option which we
+# can do through the BYPRODUCTS feature of CMake. See
+# https://cmake.org/cmake/help/latest/policy/CMP0058.html
+#
+# Unfortunately BYPRODUCTS behaves strangely with the Makefile generator: it
+# marks FBVF as generated and then CMake itself will `touch` it on every build,
+# meaning that using BYPRODUCTS will cause fish_version.o to be rebuilt
+# unconditionally with the Makefile generator. Thus we want to use the
+# natural-and-naive approach for Makefiles.
+
+# **IMPORTANT** If you touch these build rules, please test both Ninja and
+# Makefile generators with both a clean and dirty git tree. Verify that both
+# generated build systems rebuild fish when the git tree goes from dirty to
+# clean (and vice versa), and verify they do NOT rebuild it when the git tree
+# stays the same (incremental builds must be fast).
+
+# Just a handy abbreviation.
+SET(FBVF FISH-BUILD-VERSION-FILE)
+
+# TODO: find a cleaner way to do this.
+IF (${CMAKE_GENERATOR} STREQUAL Ninja)
+  SET(FBVF-OUTPUT fish-build-version-witness.txt)
+  SET(CFBVF-BYPRODUCTS ${FBVF})
+ELSE(${CMAKE_GENERATOR} STREQUAL Ninja)
+  SET(FBVF-OUTPUT ${FBVF})
+  SET(CFBVF-BYPRODUCTS)
+ENDIF(${CMAKE_GENERATOR} STREQUAL Ninja)
+
+# Set up the version targets
+ADD_CUSTOM_TARGET(CHECK-FISH-BUILD-VERSION-FILE
+                  COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/build_tools/git_version_gen.sh
+                  BYPRODUCTS ${CFBVF-BYPRODUCTS})
+
+ADD_CUSTOM_COMMAND(OUTPUT ${FBVF-OUTPUT}
+                    DEPENDS CHECK-FISH-BUILD-VERSION-FILE)
diff --git a/configure.ac b/configure.ac
index c33107b53..4f923266d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -12,7 +12,7 @@ m4_syscmd([build_tools/git_version_gen.sh 2>/dev/null])
 
 AC_PREREQ([2.60])
 AC_INIT(fish,
-        m4_esyscmd([cut -f 3 -d ' ' FISH-BUILD-VERSION-FILE | tr -d '\n']),
+        m4_esyscmd([cut -f 2 -d '=' FISH-BUILD-VERSION-FILE | tr -d '"\n']),
         fish-users@lists.sourceforge.net)
 ac_clean_files=a.out.dSYM
 
diff --git a/src/fish_version.cpp b/src/fish_version.cpp
index d371132f9..e64ba878e 100644
--- a/src/fish_version.cpp
+++ b/src/fish_version.cpp
@@ -5,7 +5,12 @@
 #include "fish_version.h"
 
 #ifndef FISH_BUILD_VERSION
-#include "fish-build-version.h"
+// The contents of FISH-BUILD-VERSION-FILE looks like:
+// FISH_BUILD_VERSION="2.7.1-62-gc0480092-dirty"
+// Arrange for it to become a variable.
+static const char *
+#include "FISH-BUILD-VERSION-FILE"
+    ;
 #endif
 
 /// Return fish shell version.