diff --git a/cabal-install/Distribution/Client/ProjectBuilding.hs b/cabal-install/Distribution/Client/ProjectBuilding.hs
index 1e91b5e187c..10a2a93df03 100644
--- a/cabal-install/Distribution/Client/ProjectBuilding.hs
+++ b/cabal-install/Distribution/Client/ProjectBuilding.hs
@@ -936,6 +936,13 @@ buildAndInstallUnpackedPackage verbosity
     annotateFailure mlogFile BuildFailed $
       setup buildCommand buildFlags
 
+    -- Haddock phase
+    whenHaddock $ do
+      when isParallelBuild $
+        notice verbosity $ "Generating " ++ dispname ++ " documentation..."
+      annotateFailureNoLog HaddocksFailed $
+        setup haddockCommand haddockFlags
+
     -- Install phase
     annotateFailure mlogFile InstallFailed $ do
 
@@ -954,7 +961,7 @@ buildAndInstallUnpackedPackage verbosity
             -- While this breaks the prefix-relocatable property of the lirbaries
             -- it is necessary on macOS to stay under the load command limit of the
             -- macOS mach-o linker. See also @PackageHash.hashedInstalledPackageIdVeryShort@.
-            otherFiles <- filter (not . isPrefixOf entryDir) <$> listFilesRecursive tmpDir 
+            otherFiles <- filter (not . isPrefixOf entryDir) <$> listFilesRecursive tmpDir
             -- here's where we could keep track of the installed files ourselves
             -- if we wanted to by making a manifest of the files in the tmp dir
             return (entryDir, otherFiles)
@@ -1022,6 +1029,10 @@ buildAndInstallUnpackedPackage verbosity
 
     isParallelBuild = buildSettingNumJobs >= 2
 
+    whenHaddock action
+      | elabBuildHaddocks pkg = action
+      | otherwise             = return ()
+
     configureCommand = Cabal.configureCommand defaultProgramDb
     configureFlags v = flip filterConfigureFlags v $
                        setupHsConfigureFlags rpkg pkgshared
@@ -1031,6 +1042,10 @@ buildAndInstallUnpackedPackage verbosity
     buildCommand     = Cabal.buildCommand defaultProgramDb
     buildFlags   _   = setupHsBuildFlags pkg pkgshared verbosity builddir
 
+    haddockCommand   = Cabal.haddockCommand
+    haddockFlags _   = setupHsHaddockFlags pkg pkgshared
+                                           verbosity builddir
+
     generateInstalledPackageInfo :: IO InstalledPackageInfo
     generateInstalledPackageInfo =
       withTempInstalledPackageInfoFile
diff --git a/cabal-install/Distribution/Client/ProjectConfig/Legacy.hs b/cabal-install/Distribution/Client/ProjectConfig/Legacy.hs
index b0c048b0d4a..f6ce8e45b51 100644
--- a/cabal-install/Distribution/Client/ProjectConfig/Legacy.hs
+++ b/cabal-install/Distribution/Client/ProjectConfig/Legacy.hs
@@ -490,7 +490,10 @@ convertToLegacySharedConfig :: ProjectConfig -> LegacySharedConfig
 convertToLegacySharedConfig
     ProjectConfig {
       projectConfigBuildOnly     = ProjectConfigBuildOnly {..},
-      projectConfigShared        = ProjectConfigShared {..}
+      projectConfigShared        = ProjectConfigShared {..},
+      projectConfigAllPackages   = PackageConfig {
+        packageConfigDocumentation
+      }
     } =
 
     LegacySharedConfig {
@@ -536,7 +539,7 @@ convertToLegacySharedConfig
     }
 
     installFlags = InstallFlags {
-      installDocumentation     = mempty,
+      installDocumentation     = packageConfigDocumentation,
       installHaddockIndex      = projectConfigHaddockIndex,
       installDest              = Flag NoCopyDest,
       installDryRun            = projectConfigDryRun,
diff --git a/cabal-install/Distribution/Client/ProjectPlanning.hs b/cabal-install/Distribution/Client/ProjectPlanning.hs
index 4cb7ebb1c22..d4d09407e0e 100644
--- a/cabal-install/Distribution/Client/ProjectPlanning.hs
+++ b/cabal-install/Distribution/Client/ProjectPlanning.hs
@@ -1675,7 +1675,8 @@ elaborateInstallPlan verbosity platform compiler compilerprogdb pkgConfigDB
         elabTestTargets     = []
         elabBenchTargets    = []
         elabReplTarget      = Nothing
-        elabBuildHaddocks   = False
+        elabBuildHaddocks   =
+          perPkgOptionFlag pkgid False packageConfigDocumentation
 
         elabPkgSourceLocation = srcloc
         elabPkgSourceHash   = Map.lookup pkgid sourcePackageHashes