diff --git a/lua/telescope/sorters.lua b/lua/telescope/sorters.lua
index 6817c97..c1b4b0f 100644
--- a/lua/telescope/sorters.lua
+++ b/lua/telescope/sorters.lua
@@ -511,44 +511,52 @@ sorters.get_levenshtein_sorter = function()
   }
 end
 
-local substr_highlighter = function(_, prompt, display)
-  local highlights = {}
-  display = display:lower()
+local substr_highlighter = function(make_display)
+  return function(_, prompt, display)
+    local highlights = {}
+    display = make_display(prompt, display)
 
-  local search_terms = util.max_split(prompt, "%s")
-  local hl_start, hl_end
+    local search_terms = util.max_split(prompt, "%s")
+    local hl_start, hl_end
 
-  for _, word in pairs(search_terms) do
-    hl_start, hl_end = display:find(word, 1, true)
-    if hl_start then
-      table.insert(highlights, { start = hl_start, finish = hl_end })
+    for _, word in pairs(search_terms) do
+      hl_start, hl_end = display:find(word, 1, true)
+      if hl_start then
+        table.insert(highlights, { start = hl_start, finish = hl_end })
+      end
     end
-  end
 
-  return highlights
+    return highlights
+  end
 end
 
 sorters.get_substr_matcher = function()
+  local make_display = vim.o.smartcase
+      and function(prompt, display)
+        local has_upper_case = not not prompt:match "%u"
+        return has_upper_case and display or display:lower()
+      end
+    or function(_, display)
+      return display:lower()
+    end
+
   return Sorter:new {
-    highlighter = substr_highlighter,
+    highlighter = substr_highlighter(make_display),
     scoring_function = function(_, prompt, _, entry)
       if #prompt == 0 then
         return 1
       end
 
-      local display = entry.ordinal:lower()
+      local display = make_display(prompt, entry.ordinal)
 
       local search_terms = util.max_split(prompt, "%s")
-      local matched = 0
-      local total_search_terms = 0
       for _, word in pairs(search_terms) do
-        total_search_terms = total_search_terms + 1
-        if display:find(word, 1, true) then
-          matched = matched + 1
+        if not display:find(word, 1, true) then
+          return -1
         end
       end
 
-      return matched == total_search_terms and entry.index or -1
+      return entry.index
     end,
   }
 end
diff --git a/lua/tests/automated/sorters_spec.lua b/lua/tests/automated/sorters_spec.lua
new file mode 100644
index 0000000..f3453a2
--- /dev/null
+++ b/lua/tests/automated/sorters_spec.lua
@@ -0,0 +1,84 @@
+local sorters = require "telescope.sorters"
+
+describe("get_substr_matcher", function()
+  local function with_smartcase(smartcase, case)
+    local original = vim.o.smartcase
+    vim.o.smartcase = smartcase
+
+    describe("scoring_function", function()
+      it(case.msg, function()
+        local matcher = sorters.get_substr_matcher()
+        assert.are.same(case.expected_score, matcher.scoring_function(_, case.prompt, _, case.entry))
+      end)
+    end)
+
+    describe("highlighter", function()
+      it("returns valid highlights", function()
+        local matcher = sorters.get_substr_matcher()
+        local highlights = matcher.highlighter(_, case.prompt, case.entry.ordinal)
+        table.sort(highlights, function(a, b)
+          return a.start < b.start
+        end)
+        assert.are.same(case.expected_highlights, highlights)
+      end)
+    end)
+
+    vim.o.smartcase = original
+  end
+
+  describe("when smartcase=OFF", function()
+    for _, case in ipairs {
+      {
+        msg = "doesn't match",
+        prompt = "abc def",
+        entry = { index = 3, ordinal = "abc d" },
+        expected_score = -1,
+        expected_highlights = { { start = 1, finish = 3 } },
+      },
+      {
+        msg = "matches with lower case letters only",
+        prompt = "abc def",
+        entry = { index = 3, ordinal = "abc def ghi" },
+        expected_score = 3,
+        expected_highlights = { { start = 1, finish = 3 }, { start = 5, finish = 7 } },
+      },
+      {
+        msg = "doesn't match with upper case letters",
+        prompt = "ABC def",
+        entry = { index = 3, ordinal = "ABC def ghi" },
+        expected_score = -1,
+        expected_highlights = { { start = 5, finish = 7 } },
+      },
+    } do
+      with_smartcase(false, case)
+    end
+  end)
+
+  describe("when smartcase=OFF", function()
+    for _, case in ipairs {
+      {
+        msg = "doesn't match",
+        prompt = "abc def",
+        entry = { index = 3, ordinal = "abc d" },
+        expected_score = -1,
+        expected_highlights = { { start = 1, finish = 3 } },
+      },
+      {
+        msg = "matches with lower case letters only",
+        prompt = "abc def",
+        entry = { index = 3, ordinal = "abc def ghi" },
+        expected_score = 3,
+        expected_highlights = { { start = 1, finish = 3 }, { start = 5, finish = 7 } },
+      },
+      {
+        msg = "matches with upper case letters",
+        prompt = "ABC def",
+        entry = { index = 3, ordinal = "ABC def ghi" },
+        expected_score = 3,
+        expected_highlights = { { start = 1, finish = 3 }, { start = 5, finish = 7 } },
+      },
+    } do
+      with_smartcase(true, case)
+    end
+  end)
+end)