diff --git a/llvm/utils/lit/lit/llvm/config.py b/llvm/utils/lit/lit/llvm/config.py
--- a/llvm/utils/lit/lit/llvm/config.py
+++ b/llvm/utils/lit/lit/llvm/config.py
@@ -407,13 +407,13 @@
         configuration's PATH."""
         # If the override is specified in the environment, use it without
         # validation.
+        tool = None
         if search_env:
             tool = self.config.environment.get(search_env)
-            if tool:
-                return tool
 
-        # Otherwise look in the path.
-        tool = lit.util.which(name, self.config.environment['PATH'])
+        if not tool:
+            # Otherwise look in the path.
+            tool = lit.util.which(name, self.config.environment['PATH'])
 
         if required and not tool:
             message = "couldn't find '{}' program".format(name)
diff --git a/llvm/utils/lit/tests/Inputs/use-tool-search-env/lit.cfg b/llvm/utils/lit/tests/Inputs/use-tool-search-env/lit.cfg
new file mode 100644
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/use-tool-search-env/lit.cfg
@@ -0,0 +1,11 @@
+import lit.formats
+config.name = 'search-env'
+config.suffixes = ['.txt']
+config.test_format = lit.formats.ShTest()
+config.test_source_root = None
+config.test_exec_root = None
+import lit.llvm
+lit.llvm.initialize(lit_config, config)
+import os.path
+lit.llvm.llvm_config.with_environment('TOOL_LOCATION', os.path.dirname(__file__) + '/test.tool')
+lit.llvm.llvm_config.use_llvm_tool('test-tool', search_env='TOOL_LOCATION')
diff --git a/llvm/utils/lit/tests/Inputs/use-tool-search-env/test.tool b/llvm/utils/lit/tests/Inputs/use-tool-search-env/test.tool
new file mode 100644
diff --git a/llvm/utils/lit/tests/Inputs/use-tool-search-env/true.txt b/llvm/utils/lit/tests/Inputs/use-tool-search-env/true.txt
new file mode 100644
--- /dev/null
+++ b/llvm/utils/lit/tests/Inputs/use-tool-search-env/true.txt
@@ -0,0 +1 @@
+# RUN: true
diff --git a/llvm/utils/lit/tests/use-tool-search-env.py b/llvm/utils/lit/tests/use-tool-search-env.py
new file mode 100644
--- /dev/null
+++ b/llvm/utils/lit/tests/use-tool-search-env.py
@@ -0,0 +1,7 @@
+## Show that lit reports the path to tools picked up via the use_llvm_tool
+## function when the tool is found via an environment variable.
+
+# RUN: %{lit} %{inputs}/use-tool-search-env 2>&1 | \
+# RUN:   FileCheck %s -DDIR=%p
+
+# CHECK: note: using test-tool: [[DIR]]{{[\\/]}}Inputs{{[\\/]}}use-tool-search-env{{[\\/]}}test.tool