diff --git a/ale_linters/c/ccls.vim b/ale_linters/c/ccls.vim
index 0aad0a3d..d0fa566e 100644
--- a/ale_linters/c/ccls.vim
+++ b/ale_linters/c/ccls.vim
@@ -9,7 +9,9 @@ function! ale_linters#c#ccls#GetProjectRoot(buffer) abort
 
     if empty(l:project_root)
         let l:project_root = ale#path#FindNearestFile(a:buffer, 'compile_commands.json')
-    elseif empty(l:project_root)
+    endif
+
+    if empty(l:project_root)
         let l:project_root = ale#path#FindNearestFile(a:buffer, '.ccls')
     endif
 
diff --git a/ale_linters/cpp/ccls.vim b/ale_linters/cpp/ccls.vim
index e63849c3..f1604f30 100644
--- a/ale_linters/cpp/ccls.vim
+++ b/ale_linters/cpp/ccls.vim
@@ -9,7 +9,9 @@ function! ale_linters#cpp#ccls#GetProjectRoot(buffer) abort
 
     if empty(l:project_root)
         let l:project_root = ale#path#FindNearestFile(a:buffer, 'compile_commands.json')
-    elseif empty(l:project_root)
+    endif
+
+    if empty(l:project_root)
         let l:project_root = ale#path#FindNearestFile(a:buffer, '.ccls')
     endif
 
diff --git a/ale_linters/objc/ccls.vim b/ale_linters/objc/ccls.vim
index f354c7d7..e6736df7 100644
--- a/ale_linters/objc/ccls.vim
+++ b/ale_linters/objc/ccls.vim
@@ -9,7 +9,9 @@ function! ale_linters#objc#ccls#GetProjectRoot(buffer) abort
 
     if empty(l:project_root)
         let l:project_root = ale#path#FindNearestFile(a:buffer, 'compile_commands.json')
-    elseif empty(l:project_root)
+    endif
+
+    if empty(l:project_root)
         let l:project_root = ale#path#FindNearestFile(a:buffer, '.ccls')
     endif
 
diff --git a/doc/ale.txt b/doc/ale.txt
index 00765e73..e8e3b477 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -378,8 +378,8 @@ Notes:
 * Awk: `gawk`
 * Bash: `language-server`, `shell` (-n flag), `shellcheck`, `shfmt`
 * Bourne Shell: `shell` (-n flag), `shellcheck`, `shfmt`
-* C: `cppcheck`, `cpplint`!!, `clang`, `clangd`, `clangtidy`!!, `clang-format`, `cquery`, `flawfinder`, `gcc`, `uncrustify`
-* C++ (filetype cpp): `clang`, `clangd`, `clangcheck`!!, `clangtidy`!!, `clang-format`, `clazy`!!, `cppcheck`, `cpplint`!!, `cquery`, `flawfinder`, `gcc`, `uncrustify`
+* C: `cppcheck`, `cpplint`!!, `clang`, `clangd`, `clangtidy`!!, `clang-format`, `cquery`, `flawfinder`, `gcc`, `uncrustify`, `ccls`
+* C++ (filetype cpp): `clang`, `clangd`, `clangcheck`!!, `clangtidy`!!, `clang-format`, `clazy`!!, `cppcheck`, `cpplint`!!, `cquery`, `flawfinder`, `gcc`, `uncrustify`, `ccls`
 * CUDA: `nvcc`!!
 * C#: `mcs`, `mcsc`!!, `uncrustify`
 * Chef: `foodcritic`
@@ -431,7 +431,7 @@ Notes:
 * Nim: `nim check`!!
 * nix: `nix-instantiate`
 * nroff: `alex`!!, `proselint`, `write-good`
-* Objective-C: `clang`, `clangd`, `uncrustify`
+* Objective-C: `clang`, `clangd`, `uncrustify`, `ccls`
 * Objective-C++: `clang`, `clangd`, `uncrustify`
 * OCaml: `merlin` (see |ale-ocaml-merlin|), `ols`, `ocamlformat`
 * Pawn: `uncrustify`
diff --git a/test/command_callback/ccls_paths/with_compile_commands_json/compile_commands.json b/test/command_callback/ccls_paths/with_compile_commands_json/compile_commands.json
new file mode 100644
index 00000000..e69de29b
diff --git a/test/command_callback/test_c_ccls_command_callbacks.vader b/test/command_callback/test_c_ccls_command_callbacks.vader
new file mode 100644
index 00000000..b8f3ab5b
--- /dev/null
+++ b/test/command_callback/test_c_ccls_command_callbacks.vader
@@ -0,0 +1,43 @@
+" Author: Ye Jingchen <ye.jingchen@gmail.com>, Ben Falconer <ben@falconers.me.uk>
+" Description: A language server for C
+
+Before:
+  call ale#assert#SetUpLinterTest('c', 'ccls')
+
+After:
+  call ale#assert#TearDownLinterTest()
+
+Execute(The project root should be detected correctly using compile_commands.json file):
+  AssertLSPProject ''
+
+  call ale#test#SetFilename('ccls_paths/with_compile_commands_json/dummy.c')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/ccls_paths/with_compile_commands_json')
+
+Execute(The project root should be detected correctly using .ccls file):
+  AssertLSPProject ''
+
+  call ale#test#SetFilename('ccls_paths/with_ccls/dummy.c')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/ccls_paths/with_ccls')
+
+Execute(The project root should be detected correctly using .ccls-root file):
+  AssertLSPProject ''
+
+  call ale#test#SetFilename('ccls_paths/with_ccls-root/dummy.c')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/ccls_paths/with_ccls-root')
+
+Execute(The executable should be configurable):
+  AssertLinter 'ccls', ale#Escape('ccls')
+
+  let b:ale_c_ccls_executable = 'foobar'
+
+  AssertLinter 'foobar', ale#Escape('foobar')
+
+Execute(The initialization options should be configurable):
+  AssertLSPOptions {}
+
+  let b:ale_c_ccls_init_options = { 'cacheDirectory': '/tmp/ccls' }
+
+  AssertLSPOptions { 'cacheDirectory': '/tmp/ccls' }
diff --git a/test/command_callback/test_cpp_ccls_command_callbacks.vader b/test/command_callback/test_cpp_ccls_command_callbacks.vader
new file mode 100644
index 00000000..38947acf
--- /dev/null
+++ b/test/command_callback/test_cpp_ccls_command_callbacks.vader
@@ -0,0 +1,43 @@
+" Author: Ye Jingchen <ye.jingchen@gmail.com>, Ben Falconer <ben@falconers.me.uk>
+" Description: A language server for C++
+
+Before:
+  call ale#assert#SetUpLinterTest('cpp', 'ccls')
+
+After:
+  call ale#assert#TearDownLinterTest()
+
+Execute(The project root should be detected correctly using compile_commands.json file):
+  AssertLSPProject ''
+
+  call ale#test#SetFilename('ccls_paths/with_compile_commands_json/dummy.cpp')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/ccls_paths/with_compile_commands_json')
+
+Execute(The project root should be detected correctly using .ccls file):
+  AssertLSPProject ''
+
+  call ale#test#SetFilename('ccls_paths/with_ccls/dummy.cpp')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/ccls_paths/with_ccls')
+
+Execute(The project root should be detected correctly using .ccls-root file):
+  AssertLSPProject ''
+
+  call ale#test#SetFilename('ccls_paths/with_ccls-root/dummy.cpp')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/ccls_paths/with_ccls-root')
+
+Execute(The executable should be configurable):
+  AssertLinter 'ccls', ale#Escape('ccls')
+
+  let b:ale_cpp_ccls_executable = 'foobar'
+
+  AssertLinter 'foobar', ale#Escape('foobar')
+
+Execute(The initialization options should be configurable):
+  AssertLSPOptions {}
+
+  let b:ale_cpp_ccls_init_options = { 'cacheDirectory': '/tmp/ccls' }
+
+  AssertLSPOptions { 'cacheDirectory': '/tmp/ccls' }
diff --git a/test/command_callback/test_objc_ccls_command_callbacks.vader b/test/command_callback/test_objc_ccls_command_callbacks.vader
new file mode 100644
index 00000000..9d0c7690
--- /dev/null
+++ b/test/command_callback/test_objc_ccls_command_callbacks.vader
@@ -0,0 +1,40 @@
+Before:
+  call ale#assert#SetUpLinterTest('objc', 'ccls')
+
+After:
+  call ale#assert#TearDownLinterTest()
+
+Execute(The project root should be detected correctly using compile_commands.json file):
+  AssertLSPProject ''
+
+  call ale#test#SetFilename('ccls_paths/with_compile_commands_json/dummy.m')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/ccls_paths/with_compile_commands_json')
+
+Execute(The project root should be detected correctly using .ccls file):
+  AssertLSPProject ''
+
+  call ale#test#SetFilename('ccls_paths/with_ccls/dummy.m')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/ccls_paths/with_ccls')
+
+Execute(The project root should be detected correctly using .ccls-root file):
+  AssertLSPProject ''
+
+  call ale#test#SetFilename('ccls_paths/with_ccls-root/dummy.m')
+
+  AssertLSPProject ale#path#Simplify(g:dir . '/ccls_paths/with_ccls-root')
+
+Execute(The executable should be configurable):
+  AssertLinter 'ccls', ale#Escape('ccls')
+
+  let b:ale_objc_ccls_executable = 'foobar'
+
+  AssertLinter 'foobar', ale#Escape('foobar')
+
+Execute(The initialization options should be configurable):
+  AssertLSPOptions {}
+
+  let b:ale_objc_ccls_init_options = { 'cacheDirectory': '/tmp/ccls' }
+
+  AssertLSPOptions { 'cacheDirectory': '/tmp/ccls' }