diff --git a/cabal-install/Distribution/Client/ProjectConfig.hs b/cabal-install/Distribution/Client/ProjectConfig.hs
index f4d4ef42c86..26a16c18064 100644
--- a/cabal-install/Distribution/Client/ProjectConfig.hs
+++ b/cabal-install/Distribution/Client/ProjectConfig.hs
@@ -65,7 +65,7 @@ import Distribution.Client.GlobalFlags
 import Distribution.Client.BuildReports.Types
          ( ReportLevel(..) )
 import Distribution.Client.Config
-         ( loadConfig, defaultConfigFile )
+         ( loadConfig, getConfigFilePath )
 
 import Distribution.Solver.Types.SourcePackage
 import Distribution.Solver.Types.Settings
@@ -413,9 +413,9 @@ renderBadProjectRoot (BadProjectRootExplicitFile projectFile) =
 -- | Read all the config relevant for a project. This includes the project
 -- file if any, plus other global config.
 --
-readProjectConfig :: Verbosity -> DistDirLayout -> Rebuild ProjectConfig
-readProjectConfig verbosity distDirLayout = do
-    global <- readGlobalConfig             verbosity
+readProjectConfig :: Verbosity -> Flag FilePath -> DistDirLayout -> Rebuild ProjectConfig
+readProjectConfig verbosity configFileFlag distDirLayout = do
+    global <- readGlobalConfig             verbosity configFileFlag
     local  <- readProjectLocalConfig       verbosity distDirLayout
     freeze <- readProjectLocalFreezeConfig verbosity distDirLayout
     extra  <- readProjectLocalExtraConfig  verbosity distDirLayout
@@ -546,15 +546,12 @@ writeProjectConfigFile file =
 
 -- | Read the user's @~/.cabal/config@ file.
 --
-readGlobalConfig :: Verbosity -> Rebuild ProjectConfig
-readGlobalConfig verbosity = do
-    config     <- liftIO (loadConfig verbosity mempty)
-    configFile <- liftIO defaultConfigFile
+readGlobalConfig :: Verbosity -> Flag FilePath -> Rebuild ProjectConfig
+readGlobalConfig verbosity configFileFlag = do
+    config     <- liftIO (loadConfig verbosity configFileFlag)
+    configFile <- liftIO (getConfigFilePath configFileFlag)
     monitorFiles [monitorFileHashed configFile]
     return (convertLegacyGlobalConfig config)
-    --TODO: do this properly, there's several possible locations
-    -- and env vars, and flags for selecting the global config
-
 
 reportParseResult :: Verbosity -> String -> FilePath -> ParseResult a -> IO a
 reportParseResult verbosity _filetype filename (ParseOk warnings x) = do
diff --git a/cabal-install/Distribution/Client/ProjectConfig/Legacy.hs b/cabal-install/Distribution/Client/ProjectConfig/Legacy.hs
index 7bb99f7835c..dd1b39eafcf 100644
--- a/cabal-install/Distribution/Client/ProjectConfig/Legacy.hs
+++ b/cabal-install/Distribution/Client/ProjectConfig/Legacy.hs
@@ -270,7 +270,7 @@ convertLegacyAllPackageFlags globalFlags configFlags
     ProjectConfigShared{..}
   where
     GlobalFlags {
-      globalConfigFile        = _, -- TODO: [required feature]
+      globalConfigFile        = projectConfigConfigFile,
       globalSandboxConfigFile = _, -- ??
       globalRemoteRepos       = projectConfigRemoteRepos,
       globalLocalRepos        = projectConfigLocalRepos
@@ -466,7 +466,7 @@ convertToLegacySharedConfig
     globalFlags = GlobalFlags {
       globalVersion           = mempty,
       globalNumericVersion    = mempty,
-      globalConfigFile        = mempty,
+      globalConfigFile        = projectConfigConfigFile,
       globalSandboxConfigFile = mempty,
       globalConstraintsFile   = mempty,
       globalRemoteRepos       = projectConfigRemoteRepos,
diff --git a/cabal-install/Distribution/Client/ProjectConfig/Types.hs b/cabal-install/Distribution/Client/ProjectConfig/Types.hs
index 6dd6be5d23d..0ff1caecf9b 100644
--- a/cabal-install/Distribution/Client/ProjectConfig/Types.hs
+++ b/cabal-install/Distribution/Client/ProjectConfig/Types.hs
@@ -154,6 +154,7 @@ data ProjectConfigBuildOnly
 data ProjectConfigShared
    = ProjectConfigShared {
        projectConfigDistDir           :: Flag FilePath,
+       projectConfigConfigFile        :: Flag FilePath,
        projectConfigProjectFile       :: Flag FilePath,
        projectConfigHcFlavor          :: Flag CompilerFlavor,
        projectConfigHcPath            :: Flag FilePath,
diff --git a/cabal-install/Distribution/Client/ProjectPlanning.hs b/cabal-install/Distribution/Client/ProjectPlanning.hs
index a36745e50c3..d8cd7f457c9 100644
--- a/cabal-install/Distribution/Client/ProjectPlanning.hs
+++ b/cabal-install/Distribution/Client/ProjectPlanning.hs
@@ -313,6 +313,10 @@ rebuildProjectConfig verbosity
     return (projectConfig <> cliConfig, localPackages)
 
   where
+    ProjectConfigShared {
+      projectConfigConfigFile
+    } = projectConfigShared cliConfig
+
     fileMonitorProjectConfig = newFileMonitor (distProjectCacheFile "config")
 
     -- Read the cabal.project (or implicit config) and combine it with
@@ -325,7 +329,7 @@ rebuildProjectConfig verbosity
         createDirectoryIfMissingVerbose verbosity True distDirectory
         createDirectoryIfMissingVerbose verbosity True distProjectCacheDirectory
 
-      readProjectConfig verbosity distDirLayout
+      readProjectConfig verbosity projectConfigConfigFile distDirLayout
 
     -- Look for all the cabal packages in the project
     -- some of which may be local src dirs, tarballs etc
diff --git a/cabal-install/tests/UnitTests/Distribution/Client/ProjectConfig.hs b/cabal-install/tests/UnitTests/Distribution/Client/ProjectConfig.hs
index ee37cb37289..08ac3277f73 100644
--- a/cabal-install/tests/UnitTests/Distribution/Client/ProjectConfig.hs
+++ b/cabal-install/tests/UnitTests/Distribution/Client/ProjectConfig.hs
@@ -202,6 +202,7 @@ hackProjectConfigShared :: ProjectConfigShared -> ProjectConfigShared
 hackProjectConfigShared config =
     config {
       projectConfigProjectFile = mempty, -- not present within project files
+      projectConfigConfigFile  = mempty, -- dito
       projectConfigConstraints =
       --TODO: [required eventually] parse ambiguity in constraint
       -- "pkgname -any" as either any version or disabled flag "any".
@@ -391,6 +392,7 @@ instance Arbitrary ProjectConfigShared where
       ProjectConfigShared
         <$> arbitraryFlag arbitraryShortToken
         <*> arbitraryFlag arbitraryShortToken
+        <*> arbitraryFlag arbitraryShortToken
         <*> arbitrary
         <*> arbitraryFlag arbitraryShortToken
         <*> arbitraryFlag arbitraryShortToken
@@ -433,7 +435,8 @@ instance Arbitrary ProjectConfigShared where
                                , projectConfigStrongFlags = x18
                                , projectConfigAllowBootLibInstalls = x19
                                , projectConfigPerComponent = x20
-                               , projectConfigIndependentGoals = x21 } =
+                               , projectConfigIndependentGoals = x21
+                               , projectConfigConfigFile = x22 } =
       [ ProjectConfigShared { projectConfigDistDir = x00'
                             , projectConfigProjectFile = x01'
                             , projectConfigHcFlavor = x02'
@@ -455,18 +458,19 @@ instance Arbitrary ProjectConfigShared where
                             , projectConfigStrongFlags = x18'
                             , projectConfigAllowBootLibInstalls = x19'
                             , projectConfigPerComponent = x20'
-                            , projectConfigIndependentGoals = x21' }
+                            , projectConfigIndependentGoals = x21'
+                            , projectConfigConfigFile = x22' }
       | ((x00', x01', x02', x03', x04'),
          (x05', x06', x07', x08', x09'),
          (x10', x11', x12', x13', x14'),
          (x15', x16', x17', x18', x19'),
-          x20', x21')
+          x20', x21', x22')
           <- shrink
                ((x00, x01, x02, fmap NonEmpty x03, fmap NonEmpty x04),
                 (x05, x06, x07, x08, preShrink_Constraints x09),
                 (x10, x11, x12, x13, x14),
                 (x15, x16, x17, x18, x19),
-                 x20, x21)
+                 x20, x21, x22)
       ]
       where
         preShrink_Constraints  = map fst