diff --git a/Library/Homebrew/brew.sh b/Library/Homebrew/brew.sh
index 6d5720e534..421129f8b5 100644
--- a/Library/Homebrew/brew.sh
+++ b/Library/Homebrew/brew.sh
@@ -374,6 +374,26 @@ then
   export HOMEBREW_BOTTLE_DOMAIN="$HOMEBREW_BOTTLE_DEFAULT_DOMAIN"
 fi
 
+HOMEBREW_DEFAULT_BREW_GIT_REMOTE="https://github.com/Homebrew/brew"
+if [[ -z "$HOMEBREW_BREW_GIT_REMOTE" ]]
+then
+  HOMEBREW_BREW_GIT_REMOTE="$HOMEBREW_DEFAULT_BREW_GIT_REMOTE"
+fi
+export HOMEBREW_BREW_GIT_REMOTE
+
+if [[ -n "$HOMEBREW_MACOS" ]] || [[ -n "$HOMEBREW_FORCE_HOMEBREW_ON_LINUX" ]]
+then
+  HOMEBREW_DEFAULT_CORE_GIT_REMOTE="https://github.com/Homebrew/homebrew-core"
+else
+  HOMEBREW_DEFAULT_CORE_GIT_REMOTE="https://github.com/Homebrew/linuxbrew-core"
+fi
+
+if [[ -z "$HOMEBREW_CORE_GIT_REMOTE" ]]
+then
+  HOMEBREW_CORE_GIT_REMOTE="$HOMEBREW_DEFAULT_CORE_GIT_REMOTE"
+fi
+export HOMEBREW_CORE_GIT_REMOTE
+
 if [[ -f "$HOMEBREW_LIBRARY/Homebrew/cmd/$HOMEBREW_COMMAND.sh" ]]
 then
   HOMEBREW_BASH_COMMAND="$HOMEBREW_LIBRARY/Homebrew/cmd/$HOMEBREW_COMMAND.sh"
diff --git a/Library/Homebrew/cmd/update.sh b/Library/Homebrew/cmd/update.sh
index 745ff6372b..cf8aa8879b 100644
--- a/Library/Homebrew/cmd/update.sh
+++ b/Library/Homebrew/cmd/update.sh
@@ -23,14 +23,6 @@ git() {
 }
 
 git_init_if_necessary() {
-  BREW_OFFICIAL_REMOTE="https://github.com/Homebrew/brew"
-  if [[ -n "$HOMEBREW_MACOS" ]] || [[ -n "$HOMEBREW_FORCE_HOMEBREW_ON_LINUX" ]]
-  then
-    CORE_OFFICIAL_REMOTE="https://github.com/Homebrew/homebrew-core"
-  else
-    CORE_OFFICIAL_REMOTE="https://github.com/Homebrew/linuxbrew-core"
-  fi
-
   safe_cd "$HOMEBREW_REPOSITORY"
   if [[ ! -d ".git" ]]
   then
@@ -38,7 +30,7 @@ git_init_if_necessary() {
     trap '{ rm -rf .git; exit 1; }' EXIT
     git init
     git config --bool core.autocrlf false
-    git config remote.origin.url "$BREW_OFFICIAL_REMOTE"
+    git config remote.origin.url "$HOMEBREW_BREW_GIT_REMOTE"
     git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"
     latest_tag="$(git ls-remote --tags --refs -q origin | tail -n1 | cut -f2)"
     git fetch --force origin --shallow-since="$latest_tag"
@@ -56,7 +48,7 @@ git_init_if_necessary() {
     trap '{ rm -rf .git; exit 1; }' EXIT
     git init
     git config --bool core.autocrlf false
-    git config remote.origin.url "$CORE_OFFICIAL_REMOTE"
+    git config remote.origin.url "$HOMEBREW_CORE_GIT_REMOTE"
     git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"
     git fetch --force --depth=1 origin refs/heads/master:refs/remotes/origin/master
     git reset --hard origin/master
@@ -402,6 +394,24 @@ EOS
 
   git_init_if_necessary
 
+  if [[ "$HOMEBREW_DEFAULT_BREW_GIT_REMOTE" != "$HOMEBREW_BREW_GIT_REMOTE" ]]
+  then
+    safe_cd "$HOMEBREW_REPOSITORY"
+    git remote set-url origin "$HOMEBREW_BREW_GIT_REMOTE"
+    git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"
+    latest_tag="$(git ls-remote --tags --refs -q origin | tail -n1 | cut -f2)"
+    git fetch --force origin --shallow-since="$latest_tag"
+  fi
+
+  if [[ "$HOMEBREW_DEFAULT_CORE_GIT_REMOTE" != "$HOMEBREW_CORE_GIT_REMOTE" ]] &&
+     [[ -d "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core" ]]
+  then
+    safe_cd "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core"
+    git remote set-url origin "$HOMEBREW_CORE_GIT_REMOTE"
+    git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"
+    git fetch --force --depth=1 origin refs/heads/master:refs/remotes/origin/master
+  fi
+
   safe_cd "$HOMEBREW_REPOSITORY"
 
   # if an older system had a newer curl installed, change each repo's remote URL from GIT to HTTPS
@@ -409,8 +419,8 @@ EOS
         -x "$HOMEBREW_PREFIX/opt/curl/bin/curl" &&
         "$(git config remote.origin.url)" =~ ^git:// ]]
   then
-    git config remote.origin.url "$BREW_OFFICIAL_REMOTE"
-    git config -f "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core/.git/config" remote.origin.url "$CORE_OFFICIAL_REMOTE"
+    git config remote.origin.url "$HOMEBREW_BREW_GIT_REMOTE"
+    git config -f "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core/.git/config" remote.origin.url "$HOMEBREW_CORE_GIT_REMOTE"
   fi
 
   # kill all of subprocess on interrupt
diff --git a/Library/Homebrew/diagnostic.rb b/Library/Homebrew/diagnostic.rb
index 77247e746c..27b4922dca 100644
--- a/Library/Homebrew/diagnostic.rb
+++ b/Library/Homebrew/diagnostic.rb
@@ -130,7 +130,7 @@ module Homebrew
 
             With a non-standard origin, Homebrew won't update properly.
             You can solve this by setting the origin remote:
-              git -C "#{repository_path}" remote set-url origin #{Formatter.url("https://github.com/#{desired_origin}.git")}
+              git -C "#{repository_path}" remote set-url origin #{Formatter.url("https://github.com/#{desired_origin}")}
           EOS
         end
       end
@@ -560,11 +560,11 @@ module Homebrew
       end
 
       def check_brew_git_origin
-        examine_git_origin(HOMEBREW_REPOSITORY, "Homebrew/brew")
+        examine_git_origin(HOMEBREW_REPOSITORY, HOMEBREW_BREW_GIT_REMOTE)
       end
 
       def check_coretap_git_origin
-        examine_git_origin(CoreTap.instance.path, CoreTap.instance.full_name)
+        examine_git_origin(CoreTap.instance.path, HOMEBREW_CORE_GIT_REMOTE)
       end
 
       def check_casktap_git_origin
diff --git a/Library/Homebrew/extend/ARGV.rb b/Library/Homebrew/extend/ARGV.rb
index 3d5a6d5e5e..f8447dc52f 100644
--- a/Library/Homebrew/extend/ARGV.rb
+++ b/Library/Homebrew/extend/ARGV.rb
@@ -98,7 +98,7 @@ module HomebrewArgvExtension
   end
 
   def build_bottle?
-    include?("--build-bottle") || !ENV["HOMEBREW_BUILD_BOTTLE"].nil?
+    include?("--build-bottle")
   end
 
   def bottle_arch
diff --git a/Library/Homebrew/global.rb b/Library/Homebrew/global.rb
index e4e68fbdb6..8f0aa52a2b 100644
--- a/Library/Homebrew/global.rb
+++ b/Library/Homebrew/global.rb
@@ -53,6 +53,9 @@ HOMEBREW_USER_AGENT_FAKE_SAFARI =
 HOMEBREW_BOTTLE_DEFAULT_DOMAIN = ENV["HOMEBREW_BOTTLE_DEFAULT_DOMAIN"]
 HOMEBREW_BOTTLE_DOMAIN = ENV["HOMEBREW_BOTTLE_DOMAIN"]
 
+HOMEBREW_BREW_GIT_REMOTE = ENV["HOMEBREW_BREW_GIT_REMOTE"]
+HOMEBREW_CORE_GIT_REMOTE = ENV["HOMEBREW_CORE_GIT_REMOTE"]
+
 HOMEBREW_DEFAULT_PREFIX = "/usr/local"
 LINUXBREW_DEFAULT_PREFIX = "/home/linuxbrew/.linuxbrew"
 
diff --git a/Library/Homebrew/manpages/brew.1.md.erb b/Library/Homebrew/manpages/brew.1.md.erb
index 982a3378a7..2feb5b6f0f 100644
--- a/Library/Homebrew/manpages/brew.1.md.erb
+++ b/Library/Homebrew/manpages/brew.1.md.erb
@@ -152,6 +152,11 @@ Note that environment variables must have a value set to be detected. For exampl
     URL. For example, `HOMEBREW_BOTTLE_DOMAIN=http://localhost:8080` will
     cause all bottles to download from the prefix `http://localhost:8080/`.
 
+  * `HOMEBREW_BREW_GIT_REMOTE`:
+    By default, Homebrew uses `https://github.com/Homebrew/brew` as its
+    Homebrew/brew `git`(1) remote. If set, instructs Homebrew to instead use
+    the specified URL.
+
   * `HOMEBREW_BROWSER`:
     If set, Homebrew uses this setting as the browser when opening project
     homepages, instead of the OS default browser.
@@ -161,6 +166,11 @@ Note that environment variables must have a value set to be detected. For exampl
 
     *Default:* `~/Library/Caches/Homebrew`.
 
+  * `HOMEBREW_CORE_GIT_REMOTE`:
+    By default, Homebrew uses `https://github.com/Homebrew/homebrew-core` (or
+    `https://github.com/Homebrew/linuxbrew-core`) as its Homebrew/homebrew-core
+    `git`(1) remote. If set, instructs Homebrew to instead use the specified URL.
+
   * `HOMEBREW_CURLRC`:
     If set, Homebrew will not pass `-q` when invoking `curl`(1), which disables
     the use of `curlrc`.
diff --git a/docs/Manpage.md b/docs/Manpage.md
index 2b0fbe73a0..5f7cd2fb06 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -1090,6 +1090,11 @@ Note that environment variables must have a value set to be detected. For exampl
     URL. For example, `HOMEBREW_BOTTLE_DOMAIN=http://localhost:8080` will
     cause all bottles to download from the prefix `http://localhost:8080/`.
 
+  * `HOMEBREW_BREW_GIT_REMOTE`:
+    By default, Homebrew uses `https://github.com/Homebrew/brew` as its
+    Homebrew/brew `git`(1) remote. If set, instructs Homebrew to instead use
+    the specified URL.
+
   * `HOMEBREW_BROWSER`:
     If set, Homebrew uses this setting as the browser when opening project
     homepages, instead of the OS default browser.
@@ -1099,6 +1104,11 @@ Note that environment variables must have a value set to be detected. For exampl
 
     *Default:* `~/Library/Caches/Homebrew`.
 
+  * `HOMEBREW_CORE_GIT_REMOTE`:
+    By default, Homebrew uses `https://github.com/Homebrew/homebrew-core` (or
+    `https://github.com/Homebrew/linuxbrew-core`) as its Homebrew/homebrew-core
+    `git`(1) remote. If set, instructs Homebrew to instead use the specified URL.
+
   * `HOMEBREW_CURLRC`:
     If set, Homebrew will not pass `-q` when invoking `curl`(1), which disables
     the use of `curlrc`.
diff --git a/manpages/brew.1 b/manpages/brew.1
index 5d815e774c..ece7f3924b 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -1347,6 +1347,10 @@ If set, Homebrew will use \fBbat\fR for the \fBbrew cat\fR command\.
 By default, Homebrew uses \fBhttps://homebrew\.bintray\.com/\fR as its download mirror for bottles\. If set, instructs Homebrew to instead use the specified URL\. For example, \fBHOMEBREW_BOTTLE_DOMAIN=http://localhost:8080\fR will cause all bottles to download from the prefix \fBhttp://localhost:8080/\fR\.
 .
 .TP
+\fBHOMEBREW_BREW_GIT_REMOTE\fR
+By default, Homebrew uses \fBhttps://github\.com/Homebrew/brew\fR as its Homebrew/brew \fBgit\fR(1) remote\. If set, instructs Homebrew to instead use the specified URL\.
+.
+.TP
 \fBHOMEBREW_BROWSER\fR
 If set, Homebrew uses this setting as the browser when opening project homepages, instead of the OS default browser\.
 .
@@ -1358,6 +1362,10 @@ If set, instructs Homebrew to use the specified directory as the download cache\
 \fIDefault:\fR \fB~/Library/Caches/Homebrew\fR\.
 .
 .TP
+\fBHOMEBREW_CORE_GIT_REMOTE\fR
+By default, Homebrew uses \fBhttps://github\.com/Homebrew/homebrew\-core\fR (or \fBhttps://github\.com/Homebrew/linuxbrew\-core\fR) as its Homebrew/homebrew\-core \fBgit\fR(1) remote\. If set, instructs Homebrew to instead use the specified URL\.
+.
+.TP
 \fBHOMEBREW_CURLRC\fR
 If set, Homebrew will not pass \fB\-q\fR when invoking \fBcurl\fR(1), which disables the use of \fBcurlrc\fR\.
 .