diff --git a/.travis.yml b/.travis.yml
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 # This Travis job script has been generated by a script via
 #
-#   runghc make_travis_yml_2.hs '-o' '.travis.yml' '--irc-channel=irc.freenode.org#haskell-lens' '--no-no-tests-no-bench' '--no-installed' 'cabal.project'
+#   runghc make_travis_yml_2.hs '-o' '.travis.yml' '--ghc-head' '--cabal-install-version=2.2' '--jobs=2' '--irc-channel=irc.freenode.org#haskell-lens' '--no-no-tests-no-bench' '--no-install-dependencies' '--config=cabal.haskell-ci' 'cabal.project'
 #
 # For more information, see https://github.com/hvr/multi-ghc-travis
 #
@@ -34,148 +34,38 @@
 
   - rm -rfv $HOME/.cabal/packages/head.hackage
 
-addons:
-  apt:
-    packages: &apt_packages
-      - ghc-ppa-tools
-
 matrix:
   include:
-    - compiler: "ghc-7.0.4"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-f-generic-deriving" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-f-mtl"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-f-generic-deriving -f-mtl" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ftwo"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ftwo -f-generic-deriving" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ftwo -f-mtl"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ftwo -f-generic-deriving -f-mtl" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-fthree"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-fthree -f-generic-deriving" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-fthree -f-mtl"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-fthree -f-generic-deriving -f-mtl" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ffour"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ffour -f-generic-deriving" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ffour -f-mtl"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ffour -f-generic-deriving -f-mtl" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ffive"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ffive -f-generic-deriving" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ffive -f-mtl"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.0.4"
-      env: CABALFLAGS="-ffive -f-generic-deriving -f-mtl" TEST=--disable-tests
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.2.2"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.2.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.2.2"
-      env: CABALFLAGS="-ftwo"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.2.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.2.2"
-      env: CABALFLAGS="-fthree"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.2.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.2.2"
-      env: CABALFLAGS="-ffour"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.2.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.2.2"
-      env: CABALFLAGS="-ffive"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.2.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.4.2"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.4.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.4.2"
-      env: CABALFLAGS="-ftwo"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.4.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.4.2"
-      env: CABALFLAGS="-fthree"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.4.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.4.2"
-      env: CABALFLAGS="-ffour"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.4.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.4.2"
-      env: CABALFLAGS="-ffive"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.4.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.6.3"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.6.3], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.6.3"
-      env: CABALFLAGS="-ftwo"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.6.3], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.6.3"
-      env: CABALFLAGS="-fthree"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.6.3], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.6.3"
-      env: CABALFLAGS="-ffour"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.6.3], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.6.3"
-      env: CABALFLAGS="-ffive"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.6.3], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.8.4"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.8.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.8.4"
-      env: CABALFLAGS="-ftwo"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.8.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.8.4"
-      env: CABALFLAGS="-fthree"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.8.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.8.4"
-      env: CABALFLAGS="-ffour"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.8.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.8.4"
-      env: CABALFLAGS="-ffive"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.8.4], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.10.3"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.10.3], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.10.3"
-      env: CABALFLAGS="-ffour"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.10.3], sources: [hvr-ghc]}}
-    - compiler: "ghc-7.10.3"
-      env: CABALFLAGS="-ffive"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-7.10.3], sources: [hvr-ghc]}}
-    - compiler: "ghc-8.0.2"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-8.0.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-8.0.2"
-      env: CABALFLAGS="-ffive"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-8.0.2], sources: [hvr-ghc]}}
+    - compiler: "ghc-8.4.2"
+    # env: TEST=--disable-tests BENCH=--disable-benchmarks
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.2,ghc-8.4.2], sources: [hvr-ghc]}}
     - compiler: "ghc-8.2.2"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.0,ghc-8.2.2], sources: [hvr-ghc]}}
-    - compiler: "ghc-8.4.1"
-      addons: {apt: {packages: [*apt_packages,cabal-install-2.2,ghc-8.4.1], sources: [hvr-ghc]}}
+    # env: TEST=--disable-tests BENCH=--disable-benchmarks
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.0,ghc-8.2.2], sources: [hvr-ghc]}}
+    - compiler: "ghc-8.0.2"
+    # env: TEST=--disable-tests BENCH=--disable-benchmarks
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.0,ghc-8.0.2], sources: [hvr-ghc]}}
+    - compiler: "ghc-7.10.3"
+    # env: TEST=--disable-tests BENCH=--disable-benchmarks
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.0,ghc-7.10.3], sources: [hvr-ghc]}}
+    - compiler: "ghc-7.8.4"
+    # env: TEST=--disable-tests BENCH=--disable-benchmarks
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.0,ghc-7.8.4], sources: [hvr-ghc]}}
+    - compiler: "ghc-7.6.3"
+    # env: TEST=--disable-tests BENCH=--disable-benchmarks
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.0,ghc-7.6.3], sources: [hvr-ghc]}}
+    - compiler: "ghc-7.4.2"
+    # env: TEST=--disable-tests BENCH=--disable-benchmarks
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.0,ghc-7.4.2], sources: [hvr-ghc]}}
+    - compiler: "ghc-7.2.2"
+    # env: TEST=--disable-tests BENCH=--disable-benchmarks
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.0,ghc-7.2.2], sources: [hvr-ghc]}}
+    - compiler: "ghc-7.0.4"
+    # env: TEST=--disable-tests BENCH=--disable-benchmarks
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.0,ghc-7.0.4], sources: [hvr-ghc]}}
     - compiler: "ghc-head"
       env: GHCHEAD=true
-      addons: {apt: {packages: [*apt_packages,cabal-install-head,ghc-head], sources: [hvr-ghc]}}
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-head,ghc-head], sources: [hvr-ghc]}}
 
   allow_failures:
     - compiler: "ghc-head"
@@ -201,6 +91,7 @@
   - travis_retry cabal update -v
   - "sed -i.bak 's/^jobs:/-- jobs:/' ${HOME}/.cabal/config"
   - rm -fv cabal.project cabal.project.local
+  - "sed -i.bak 's/^-- jobs:.*/jobs: 2/' ${HOME}/.cabal/config"
   # Overlay Hackage Package Index for GHC HEAD: https://github.com/hvr/head.hackage
   - |
     if $GHCHEAD; then
@@ -241,10 +132,12 @@
   - "printf 'packages: transformers-compat-*/*.cabal transformers-compat-tests-*/*.cabal\\n' > cabal.project"
   - cat cabal.project
 
+  # Build with installed constraints for packages in global-db
+  - if $INSTALLED; then echo cabal new-build -w ${HC} --disable-tests --disable-benchmarks $(${HCPKG} list --global --simple-output --names-only | sed 's/\([a-zA-Z0-9-]\{1,\}\) */--constraint="\1 installed" /g') all | sh; else echo "Not building with installed constraints"; fi
 
   # build & run tests, build benchmarks
-  - cabal new-build -w ${HC} ${CABALFLAGS} ${TEST} ${BENCH} -j2 all
-  - if [ "x$TEST" = "x--enable-tests" ]; then cabal new-test -w ${HC} ${CABALFLAGS} ${TEST} ${BENCH} all; fi
+  - cabal new-build -w ${HC} ${TEST} ${BENCH} all
+  - if [ "x$TEST" = "x--enable-tests" ]; then cabal new-test -w ${HC} ${TEST} ${BENCH} all; fi
 
   # cabal check
   - (cd transformers-compat-* && cabal check)
@@ -252,7 +145,22 @@
 
   # haddock
   - rm -rf ./dist-newstyle
-  - if $HADDOCK; then cabal new-haddock -w ${HC} ${CABALFLAGS} ${TEST} ${BENCH} all; else echo "Skipping haddock generation";fi
+  - if $HADDOCK; then cabal new-haddock -w ${HC} ${TEST} ${BENCH} all; else echo "Skipping haddock generation";fi
 
-# REGENDATA ["-o",".travis.yml","--irc-channel=irc.freenode.org#haskell-lens","--no-no-tests-no-bench","--no-installed","cabal.project"]
+  # Constraint set no-mtl
+  - if [ $HCNUMVER -ge 0 ]; then cabal new-build -w ${HC} --disable-tests --disable-benchmarks --constraint='transformers-compat -mtl' all; else echo skipping...; fi
+
+  # Constraint set no-generic-deriving
+  - if [ $HCNUMVER -ge 0 ]; then cabal new-build -w ${HC} --disable-tests --disable-benchmarks --constraint='transformers-compat -generic-deriving' all; else echo skipping...; fi
+
+  # Constraint set no-mtl-no-generic-deriving
+  - if [ $HCNUMVER -ge 0 ]; then cabal new-build -w ${HC} --disable-tests --disable-benchmarks --constraint='transformers-compat -generic-deriving' --constraint='tranformers-compat -mtl' all; else echo skipping...; fi
+
+  # Constraint set transformers-installed
+  - if [ $HCNUMVER -ge 70800 ]; then cabal new-build -w ${HC} --disable-tests --disable-benchmarks --constraint='transformers installed' all; else echo skipping...; fi
+
+  # Constraint set transformers-newer
+  - if [ $HCNUMVER -ge 0 ] && [ $HCNUMVER -lt 80500 ]; then cabal new-build -w ${HC} --disable-tests --disable-benchmarks --constraint='transformers >=0.5.5.0' all; else echo skipping...; fi
+
+# REGENDATA ["-o",".travis.yml","--ghc-head","--cabal-install-version=2.2","--jobs=2","--irc-channel=irc.freenode.org#haskell-lens","--no-no-tests-no-bench","--no-install-dependencies","--config=cabal.haskell-ci","cabal.project"]
 # EOF
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,19 @@
+0.6.2
+-----
+* `transformers-compat` now uses automatic flags instead of manual ones.
+  This has a number of benefits:
+
+  * There is no need for making several simultaneous releases to support each
+    flag combination.
+  * As a result, the `cabal-install` constraint solver should have a much
+    easier time figuring out install-plans involving `transformers-compat`.
+
+  Due to old `cabal-install` bugs, `cabal-install-1.16` and older may have a
+  harder time installing this package, so it is recommended that you use
+  `cabal-install-1.18` or later. (Or, if you must use `cabal-install-1.16` or
+  older, installing `transformers-compat` with the appropriate flags should
+  help.)
+
 0.6.1.6
 -------
 * Each of versions 0.6.1.2–0.6.1.6 is a 0.6.1 build with a different set of flags configured. Building this way allows us to work around bugs in `cabal`'s backtracker. The 0.6.1 release notes describe the changes in this version.
diff --git a/tests/transformers-compat-tests.cabal b/tests/transformers-compat-tests.cabal
--- a/tests/transformers-compat-tests.cabal
+++ b/tests/transformers-compat-tests.cabal
@@ -21,7 +21,7 @@
              , GHC == 7.10.3
              , GHC == 8.0.2
              , GHC == 8.2.2
-             , GHC == 8.4.1
+             , GHC == 8.4.2
 
 source-repository head
   type: git
diff --git a/transformers-compat.cabal b/transformers-compat.cabal
--- a/transformers-compat.cabal
+++ b/transformers-compat.cabal
@@ -1,6 +1,6 @@
 name:          transformers-compat
 category:      Compatibility
-version:       0.6.1.6
+version:       0.6.2
 license:       BSD3
 cabal-version: >= 1.8
 license-file:  LICENSE
@@ -31,7 +31,7 @@
              , GHC == 7.10.3
              , GHC == 8.0.2
              , GHC == 8.2.2
-             , GHC == 8.4.1
+             , GHC == 8.4.2
 extra-source-files:
   .travis.yml
   .ghci
@@ -52,23 +52,28 @@
 flag two
   default: False
   description: Use transformers 0.2. This will be selected by cabal picking the appropriate version.
-  manual: True
+  manual: False
 
 flag three
   default: False
-  manual: True
+  manual: False
   description: Use transformers 0.3. This will be selected by cabal picking the appropriate version.
 
 flag four
   default: False
-  manual: True
+  manual: False
   description: Use transformers 0.4. This will be selected by cabal picking the appropriate version.
 
 flag five
   default: False
-  manual: True
+  manual: False
   description: Use transformers 0.5 up until (but not including) 0.5.3. This will be selected by cabal picking the appropriate version.
 
+flag five-three
+  default: False
+  manual: False
+  description: Use transformers 0.5.3. This will be selected by cabal picking the appropriate version.
+
 flag mtl
   default: True
   manual: True
@@ -85,7 +90,11 @@
 
 library
   build-depends:
-    base >= 4.3 && < 5
+    base >= 4.3 && < 5,
+    -- These are all transformers versions we support.
+    -- each flag below splits this interval into two parts.
+    -- flag-true parts are mutually exclusive, so at least one have to be on.
+    transformers >= 0.2 && <0.6
 
   hs-source-dirs:
     src
@@ -96,31 +105,45 @@
   other-modules:
     Paths_transformers_compat
 
+  -- automatic flags
+  if flag(five-three)
+    hs-source-dirs: 0.5
+    build-depends: transformers >= 0.5.3
+  else
+    build-depends: transformers < 0.5.3
+
   if flag(five)
     hs-source-dirs: 0.5
     build-depends: transformers >= 0.5 && < 0.5.3
   else
-    if flag(four)
-      cpp-options: -DTRANSFORMERS_FOUR
-      hs-source-dirs: 0.5
-      -- Don't allow transformers-0.4.0.0
-      -- See https://github.com/ekmett/transformers-compat/issues/35
-      build-depends: transformers >= 0.4.1 && < 0.5
-    else
-      if flag(three)
-        hs-source-dirs: 0.3 0.5
-        build-depends: transformers >= 0.3 && < 0.4
-        if flag(mtl)
-          build-depends: mtl >= 2.1 && < 2.2
-      else
-        if flag(two)
-          hs-source-dirs: 0.2 0.3 0.5
-          build-depends: transformers >= 0.2 && < 0.3
-          if flag(mtl)
-            build-depends: mtl >= 2.0 && < 2.1
-        else
-          build-depends: transformers >= 0.5.3 && < 0.6
+    build-depends: transformers < 0.5 || >= 0.5.3
 
+  if flag(four)
+    cpp-options: -DTRANSFORMERS_FOUR
+    hs-source-dirs: 0.5
+    -- Don't allow transformers-0.4.0.0
+    -- See https://github.com/ekmett/transformers-compat/issues/35
+    build-depends: transformers >= 0.4.1 && < 0.5
+  else
+    build-depends: transformers < 0.4 || >= 0.5
+
+  if flag(three)
+    hs-source-dirs: 0.3 0.5
+    build-depends: transformers >= 0.3 && < 0.4
+    if flag(mtl)
+      build-depends: mtl >= 2.1 && < 2.2
+  else
+    build-depends: transformers < 0.3 || >= 0.4
+
+  if flag(two)
+    hs-source-dirs: 0.2 0.3 0.5
+    build-depends: transformers >= 0.2 && < 0.3
+    if flag(mtl)
+      build-depends: mtl >= 2.0 && < 2.1
+  else
+    build-depends: transformers >= 0.3
+
+  -- other flags
   if impl(ghc >= 7.2) || flag(generic-deriving)
     hs-source-dirs: generics
     build-depends: ghc-prim