diff --git a/src/GitTabExpansion.ps1 b/src/GitTabExpansion.ps1
index 6e0606738..5d46fc446 100644
--- a/src/GitTabExpansion.ps1
+++ b/src/GitTabExpansion.ps1
@@ -69,6 +69,22 @@ $script:gitCommandsWithParamValues = $gitParamValues.Keys -join '|'
 $script:vstsCommandsWithShortParams = $shortVstsParams.Keys -join '|'
 $script:vstsCommandsWithLongParams = $longVstsParams.Keys -join '|'
 
+# The regular expression here is roughly follows this pattern:
+#
+# <begin anchor><whitespace>*<git>(<whitespace><parameter>)*<whitespace>+<$args><whitespace>*<end anchor>
+#
+# The delimiters inside the parameter list and between some of the elements are non-newline whitespace characters ([^\S\r\n]).
+# In those instances, newlines are only allowed if they preceded by a non-newline whitespace character.
+#
+# Begin anchor (^|[;`n])
+# Whitespace   (\s*)
+# Git Command  (?<cmd>$(GetAliasPattern git))
+# Parameters   (?<params>(([^\S\r\n]|[^\S\r\n]``\r?\n)+\S+)*)
+# $args Anchor (([^\S\r\n]|[^\S\r\n]``\r?\n)+\`$args)
+# Whitespace   (\s|``\r?\n)*
+# End Anchor   ($|[|;`n])
+$script:GitProxyFunctionRegex = "(^|[;`n])(\s*)(?<cmd>$(Get-AliasPattern git))(?<params>(([^\S\r\n]|[^\S\r\n]``\r?\n)+\S+)*)(([^\S\r\n]|[^\S\r\n]``\r?\n)+\`$args)(\s|``\r?\n)*($|[|;`n])"
+
 try {
     if ($null -ne (git help -a 2>&1 | Select-String flow)) {
         $script:someCommands += 'flow'
@@ -472,6 +488,34 @@ function GitTabExpansionInternal($lastBlock, $GitStatus = $null) {
     }
 }
 
+function Expand-GitProxyFunction($command) {
+    # Make sure the incoming command matches: <Command> <Args>, so we can extract the alias/command
+    # name and the arguments being passed in.
+    if ($command -notmatch '^(?<command>\S+)([^\S\r\n]|[^\S\r\n]`\r?\n)+(?<args>([^\S\r\n]|[^\S\r\n]`\r?\n|\S)*)$') {
+        return $command
+    }
+
+    # Store arguments for replacement later
+    $arguments = $matches['args']
+
+    # Get the command name; if an alias exists, get the actual command name
+    $commandName = $matches['command']
+    if (Test-Path -Path Alias:\$commandName) {
+        $commandName = Get-Item -Path Alias:\$commandName | Select-Object -ExpandProperty 'ResolvedCommandName'
+    }
+
+    # Extract definition of git usage
+    if (Test-Path -Path Function:\$commandName) {
+        $definition = Get-Item -Path Function:\$commandName | Select-Object -ExpandProperty 'Definition'
+        if ($definition -match $script:GitProxyFunctionRegex) {
+            # Clean up the command by removing extra delimiting whitespace and backtick preceding newlines
+            return (("$($matches['cmd'].TrimStart()) $($matches['params']) $arguments") -replace '`\r?\n', ' ' -replace '\s+', ' ')
+        }
+    }
+
+    return $command
+}
+
 function WriteTabExpLog([string] $Message) {
     if (!$global:GitTabSettings.EnableLogging) { return }
 
@@ -481,6 +525,9 @@ function WriteTabExpLog([string] $Message) {
 
 if (!$UseLegacyTabExpansion -and ($PSVersionTable.PSVersion.Major -ge 6)) {
     $cmdNames = "git","tgit","gitk"
+    if ($EnableProxyFunctionExpansion) {
+        $cmdNames += Get-ChildItem -Path Function:\ | Where-Object { $_.Definition -match $script:GitProxyFunctionRegex } | Select-Object -ExpandProperty 'Name'
+    }
     $cmdNames += Get-Alias -Definition $cmdNames -ErrorAction Ignore | ForEach-Object Name
 
     Microsoft.PowerShell.Core\Register-ArgumentCompleter -CommandName $cmdNames -Native -ScriptBlock {
@@ -491,6 +538,9 @@ if (!$UseLegacyTabExpansion -and ($PSVersionTable.PSVersion.Major -ge 6)) {
         # The Expand-GitCommand expects this trailing space, so pad with a space if necessary.
         $padLength = $cursorPosition - $commandAst.Extent.StartOffset
         $textToComplete = $commandAst.ToString().PadRight($padLength, ' ').Substring(0, $padLength)
+        if ($EnableProxyFunctionExpansion) {
+            $textToComplete = Expand-GitProxyFunction($textToComplete)
+        }
 
         WriteTabExpLog "Expand: command: '$($commandAst.Extent.Text)', padded: '$textToComplete', padlen: $padLength"
         Expand-GitCommand $textToComplete
@@ -504,6 +554,9 @@ else {
 
             $line = $Context.Line
             $lastBlock = [regex]::Split($line, '[|;]')[-1].TrimStart()
+            if ($EnableProxyFunctionExpansion) {
+                $lastBlock = Expand-GitProxyFunction($lastBlock)
+            }
             $TabExpansionHasOutput.Value = $true
             WriteTabExpLog "PowerTab expand: '$lastBlock'"
             Expand-GitCommand $lastBlock
@@ -514,6 +567,9 @@ else {
 
     function TabExpansion($line, $lastWord) {
         $lastBlock = [regex]::Split($line, '[|;]')[-1].TrimStart()
+        if ($EnableProxyFunctionExpansion) {
+            $lastBlock = Expand-GitProxyFunction($lastBlock)
+        }
         $msg = "Legacy expand: '$lastBlock'"
 
         switch -regex ($lastBlock) {
diff --git a/src/posh-git.psm1 b/src/posh-git.psm1
index df90b0903..900a502f5 100644
--- a/src/posh-git.psm1
+++ b/src/posh-git.psm1
@@ -1,4 +1,4 @@
-param([bool]$ForcePoshGitPrompt, [bool]$UseLegacyTabExpansion)
+param([bool]$ForcePoshGitPrompt, [bool]$UseLegacyTabExpansion, [bool]$EnableProxyFunctionExpansion)
 
 . $PSScriptRoot\CheckRequirements.ps1 > $null
 
diff --git a/test/GitProxyFunctionExpansion.Tests.ps1 b/test/GitProxyFunctionExpansion.Tests.ps1
new file mode 100644
index 000000000..9ef606db7
--- /dev/null
+++ b/test/GitProxyFunctionExpansion.Tests.ps1
@@ -0,0 +1,363 @@
+BeforeAll {
+    . $PSScriptRoot\Shared.ps1
+}
+
+Describe 'Proxy Function Expansion Tests' {
+    Context 'Proxy Function Name TabExpansion Tests' {
+        BeforeEach {
+            if(Test-Path -Path Function:\Invoke-GitFunction) {
+                Rename-Item -Path Function:\Invoke-GitFunction -NewName Invoke-GitFunctionBackup
+            }
+            if(Test-Path -Path Alias:\igf) {
+                Rename-Item -Path Alias:\igf -NewName igfbackup
+            }
+            New-Alias -Name 'igf' -Value Invoke-GitFunction -Scope 'Script'
+        }
+        AfterEach {
+            if(Test-Path -Path Function:\Invoke-GitFunction) {
+                Remove-Item -Path Function:\Invoke-GitFunction
+            }
+            if(Test-Path -Path Function:\Invoke-GitFunctionBackup) {
+                Rename-Item Function:\Invoke-GitFunctionBackup Invoke-GitFunction
+            }
+            if(Test-Path -Path Alias:\igf) {
+                Remove-Item -Path Alias:\igf
+            }
+            if(Test-Path -Path Alias:\igfbackup) {
+                Rename-Item -Path Alias:\igfbackup -NewName igf
+            }
+        }
+        It 'Expands a proxy function with parameters' {
+            function script:Invoke-GitFunction { git checkout $args }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction -b newbranch'
+            $result | Should -Be 'git checkout -b newbranch'
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf -b newbranch')
+        }
+        It 'Expands a multiline proxy function' {
+            function script:Invoke-GitFunction { git checkout $args }
+            $result = & $module Expand-GitProxyFunction "Invoke-GitFunction ```r`n-b ```r`nnewbranch"
+            $result | Should -Be 'git checkout -b newbranch'
+            $result | Should -Be (& $module Expand-GitProxyFunction "igf ```r`n-b ```r`nnewbranch")
+        }
+        It 'Does not expand the proxy function name if there is no preceding whitespace before backtick newlines' {
+            function script:Invoke-GitFunction { git checkout $args }
+            & $module Expand-GitProxyFunction "Invoke-GitFunction```r`n-b```r`nnewbranch" | Should -Be "Invoke-GitFunction```r`n-b```r`nnewbranch"
+            & $module Expand-GitProxyFunction "igf```r`n-b```r`nnewbranch" | Should -Be "igf```r`n-b```r`nnewbranch"
+        }
+        It 'Does not expand the proxy function name if there is no preceding non-newline whitespace before any backtick newlines' {
+            function script:Invoke-GitFunction { git checkout $args }
+            & $module Expand-GitProxyFunction "Invoke-GitFunction ```r`n-b```r`nnewbranch" | Should -Be "Invoke-GitFunction ```r`n-b```r`nnewbranch"
+            & $module Expand-GitProxyFunction "igf ```r`n-b```r`nnewbranch" | Should -Be "igf ```r`n-b```r`nnewbranch"
+        }
+        It 'Does not expand the proxy function name if the preceding whitespace before backtick newlines are newlines' {
+            function script:Invoke-GitFunction { git checkout $args }
+            & $module Expand-GitProxyFunction "Invoke-GitFunction`r`n```r`n-b`r`n```r`nnewbranch" | Should -Be "Invoke-GitFunction`r`n```r`n-b`r`n```r`nnewbranch"
+            & $module Expand-GitProxyFunction "igf`r`n```r`n-b`r`n```r`nnewbranch" | Should -Be "igf`r`n```r`n-b`r`n```r`nnewbranch"
+        }
+        It 'Does not expand the proxy function if there is no trailing space' {
+            function script:Invoke-GitFunction { git checkout $args }
+            & $module Expand-GitProxyFunction 'Invoke-GitFunction' | Should -Be 'Invoke-GitFunction'
+            & $module Expand-GitProxyFunction 'igf' | Should -Be 'igf'
+        }
+    }
+    Context 'Proxy Function Definition Expansion Tests' {
+        BeforeEach {
+            if(Test-Path -Path Function:\Invoke-GitFunction) {
+                Rename-Item -Path Function:\Invoke-GitFunction -NewName Invoke-GitFunctionBackup
+            }
+            if(Test-Path -Path Alias:\igf) {
+                Rename-Item -Path Alias:\igf -NewName igfbackup
+            }
+            New-Alias -Name 'igf' -Value Invoke-GitFunction -Scope 'Script'
+        }
+        AfterEach {
+            if(Test-Path -Path Function:\Invoke-GitFunction) {
+                Remove-Item -Path Function:\Invoke-GitFunction
+            }
+            if(Test-Path -Path Function:\Invoke-GitFunctionBackup) {
+                Rename-Item Function:\Invoke-GitFunctionBackup Invoke-GitFunction
+            }
+            if(Test-Path -Path Alias:\igf) {
+                Remove-Item -Path Alias:\igf
+            }
+            if(Test-Path -Path Alias:\igfbackup) {
+                Rename-Item -Path Alias:\igfbackup -NewName igf
+            }
+        }
+        It 'Expands a single line function' {
+            function script:Invoke-GitFunction {
+                git checkout $args
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands a single line function with short parameter' {
+            function script:Invoke-GitFunction {
+                git checkout -b $args
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout -b '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands a single line function with long parameter' {
+            function script:Invoke-GitFunction {
+                git checkout --detach $args
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout --detach '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands a single line with piped function suffix' {
+            function script:Invoke-GitFunction {
+                git checkout --detach $args | Write-Host
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout --detach '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands the first line in function' {
+            function script:Invoke-GitFunction {
+                git checkout $args
+                $a = 5
+                Write-Host $null
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands the middle line in function' {
+            function script:Invoke-GitFunction {
+                $a = 5
+                git checkout $args
+                Write-Host $null
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands the last line in function' {
+            function script:Invoke-GitFunction {
+                $a = 5
+                Write-Host $null
+                git checkout $args
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands semicolon delimited functions' {
+            function script:Invoke-GitFunction {
+                $a = 5; git checkout $args; Write-Host $null;
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands mixed semicolon delimited and newline functions' {
+            function script:Invoke-GitFunction {
+                $a = 5; Write-Host $null
+                git checkout $args; Write-Host $null;
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands mixed semicolon delimited and newline multiline functions' {
+            function script:Invoke-GitFunction {
+                $a = 5; Write-Host $null
+                git `
+                checkout `
+                $args; Write-Host $null;
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands simultaneously semicolon delimited and newline functions' {
+            function script:Invoke-GitFunction {
+                $a = 5;
+                Write-Host $null;
+                git checkout $args;
+                Write-Host $null;
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands multiline function' {
+            function script:Invoke-GitFunction {
+                git `
+                checkout `
+                $args
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands multiline function that terminates with semicolon on new line' {
+            function script:Invoke-GitFunction {
+                git `
+                checkout `
+                $args `
+                ;
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands multiline function with short parameter' {
+            function script:Invoke-GitFunction {
+                git `
+                checkout `
+                -b `
+                $args
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout -b '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Expands multiline function with long parameter' {
+            function script:Invoke-GitFunction {
+                git `
+                checkout `
+                --detach `
+                $args
+            }
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result | Should -Be 'git checkout --detach '
+            $result | Should -Be (& $module Expand-GitProxyFunction 'igf ' )
+        }
+        It 'Does not expand a single line with piped function prefix' {
+            function script:Invoke-GitFunction {
+                "master" | git checkout --detach $args
+            }
+            & $module Expand-GitProxyFunction 'Invoke-GitFunction ' | Should -Be 'Invoke-GitFunction '
+            & $module Expand-GitProxyFunction 'igf ' | Should -Be 'igf '
+        }
+        It 'Does not expand function if $args is not present' {
+            function script:Invoke-GitFunction {
+                git checkout
+            }
+            & $module Expand-GitProxyFunction 'Invoke-GitFunction ' | Should -Be 'Invoke-GitFunction '
+            & $module Expand-GitProxyFunction 'igf ' | Should -Be 'igf '
+        }
+        It 'Does not expand function if $args is not attached to the git function' {
+            function script:Invoke-GitFunction {
+                $a = 5
+                git checkout
+                Write-Host $args
+            }
+            & $module Expand-GitProxyFunction 'Invoke-GitFunction ' | Should -Be 'Invoke-GitFunction '
+            & $module Expand-GitProxyFunction 'igf ' | Should -Be 'igf '
+        }
+        It 'Does not expand multiline function if $args is not attached to the git function' {
+            function script:Invoke-GitFunction {
+                $a = 5
+                git `
+                checkout
+                Write-Host $args
+            }
+            & $module Expand-GitProxyFunction 'Invoke-GitFunction ' | Should -Be 'Invoke-GitFunction '
+            & $module Expand-GitProxyFunction 'igf ' | Should -Be 'igf '
+        }
+        It 'Does not expand multiline function backtick newlines are not preceded with whitespace' {
+            function script:Invoke-GitFunction {
+                $a = 5
+                git`
+                checkout`
+                $args
+                Write-Host $null
+            }
+            & $module Expand-GitProxyFunction 'Invoke-GitFunction ' | Should -Be 'Invoke-GitFunction '
+            & $module Expand-GitProxyFunction 'igf ' | Should -Be 'igf '
+        }
+    }
+    Context 'Proxy Function Parameter Replacement Tests' {
+        BeforeEach {
+            if(Test-Path -Path Function:\Invoke-GitFunction) {
+                Rename-Item -Path Function:\Invoke-GitFunction -NewName Invoke-GitFunctionBackup
+            }
+            function script:Invoke-GitFunction { git checkout $args }
+        }
+        AfterEach {
+            if(Test-Path -Path Function:\Invoke-GitFunction) {
+                Remove-Item -Path Function:\Invoke-GitFunction
+            }
+            if(Test-Path -Path Function:\Invoke-GitFunctionBackup) {
+                Rename-Item Function:\Invoke-GitFunctionBackup Invoke-GitFunction
+            }
+        }
+        It 'Replaces parameter in $args' {
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction master'
+            $result | Should -Be 'git checkout master'
+        }
+        It 'Replaces short parameter in $args' {
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction -b master'
+            $result | Should -Be 'git checkout -b master'
+        }
+        It 'Replaces long parameter in $args' {
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction --detach master'
+            $result | Should -Be 'git checkout --detach master'
+        }
+        It 'Replaces mixed parameters in $args' {
+            $result = & $module Expand-GitProxyFunction 'Invoke-GitFunction -q -f -m --detach master'
+            $result | Should -Be 'git checkout -q -f -m --detach master'
+        }
+    }
+    Context 'Proxy Subcommand TabExpansion Tests' {
+        BeforeEach {
+            if(Test-Path -Path Function:\Invoke-GitFunction) {
+                Rename-Item -Path Function:\Invoke-GitFunction -NewName Invoke-GitFunctionBackup
+            }
+        }
+        AfterEach {
+            if(Test-Path -Path Function:\Invoke-GitFunction) {
+                Remove-Item -Path Function:\Invoke-GitFunction
+            }
+            if(Test-Path -Path Function:\Invoke-GitFunctionBackup) {
+                Rename-Item -Path Function:\Invoke-GitFunctionBackup -NewName Invoke-GitFunction
+            }
+        }
+        It 'Tab completes without subcommands' {
+            function script:Invoke-GitFunction { git whatever $args }
+            $functionText = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result = & $module GitTabExpansionInternal $functionText
+
+            $result | Should -Be @()
+        }
+        It 'Tab completes bisect subcommands' {
+            function script:Invoke-GitFunction { git bisect $args }
+            $functionText = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result = & $module GitTabExpansionInternal $functionText
+
+            $result -contains '' | Should -Be $false
+            $result -contains 'start' | Should -Be $true
+            $result -contains 'run' | Should -Be $true
+
+            $functionText = & $module Expand-GitProxyFunction 'Invoke-GitFunction s'
+            $result2 = & $module GitTabExpansionInternal $functionText
+
+            $result2 -contains 'start' | Should -Be $true
+            $result2 -contains 'skip' | Should -Be $true
+        }
+        It 'Tab completes remote subcommands' {
+            function script:Invoke-GitFunction { git remote $args }
+            $functionText = & $module Expand-GitProxyFunction 'Invoke-GitFunction '
+            $result = & $module GitTabExpansionInternal $functionText
+
+            $result -contains '' | Should -Be $false
+            $result -contains 'add' | Should -Be $true
+            $result -contains 'set-branches' | Should -Be $true
+            $result -contains 'get-url' | Should -Be $true
+            $result -contains 'update' | Should -Be $true
+
+            $functionText = & $module Expand-GitProxyFunction 'Invoke-GitFunction s'
+            $result2 = & $module GitTabExpansionInternal $functionText
+
+            $result2 -contains 'set-branches' | Should -Be $true
+            $result2 -contains 'set-head' | Should -Be $true
+            $result2 -contains 'set-url' | Should -Be $true
+        }
+    }
+}