diff --git a/clang/test/Driver/clang-offload-bundler.c b/clang/test/Driver/clang-offload-bundler.c
--- a/clang/test/Driver/clang-offload-bundler.c
+++ b/clang/test/Driver/clang-offload-bundler.c
@@ -70,9 +70,11 @@
 // RUN: not clang-offload-bundler -type=i -targets=host-%itanium_abi_triple,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu -outputs=%t.i,%t.tgt1 -inputs=%t.bundle.i -unbundle 2>&1 | FileCheck %s --check-prefix CK-ERR4
 // CK-ERR4: error: number of output files and targets should match in unbundling mode
 
-// RUN: not clang-offload-bundler -type=i -targets=host-%itanium_abi_triple,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu -inputs=%t.i,%t.tgt1,%t.tgt2.notexist -outputs=%t.bundle.i 2>&1 | FileCheck %s -DFILE=%t.tgt2.notexist --check-prefix CK-ERR5
-// RUN: not clang-offload-bundler -type=i -targets=host-%itanium_abi_triple,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu -outputs=%t.i,%t.tgt1,%t.tgt2 -inputs=%t.bundle.i.notexist -unbundle 2>&1 | FileCheck %s -DFILE=%t.bundle.i.notexist --check-prefix CK-ERR5
-// CK-ERR5: error: '[[FILE]]': {{N|n}}o such file or directory
+// RUN: not clang-offload-bundler -type=i -targets=host-%itanium_abi_triple,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu -inputs=%t.i,%t.tgt1,%t.tgt2.notexist -outputs=%t.bundle.i 2>&1 | \
+// RUN:   FileCheck %s -DFILE=%t.tgt2.notexist -DMSG=%errc_ENOENT --check-prefix CK-ERR5
+// RUN: not clang-offload-bundler -type=i -targets=host-%itanium_abi_triple,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu -outputs=%t.i,%t.tgt1,%t.tgt2 -inputs=%t.bundle.i.notexist -unbundle 2>&1 | \
+// RUN:   FileCheck %s -DFILE=%t.bundle.i.notexist -DMSG=%errc_ENOENT --check-prefix CK-ERR5
+// CK-ERR5: error: '[[FILE]]': [[MSG]]
 
 // RUN: not clang-offload-bundler -type=invalid -targets=host-%itanium_abi_triple,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu -inputs=%t.i,%t.tgt1,%t.tgt2 -outputs=%t.bundle.i 2>&1 | FileCheck %s -DTYPE=invalid --check-prefix CK-ERR6
 // CK-ERR6: error: '[[TYPE]]': invalid file type specified
diff --git a/clang/test/Frontend/output-paths.c b/clang/test/Frontend/output-paths.c
--- a/clang/test/Frontend/output-paths.c
+++ b/clang/test/Frontend/output-paths.c
@@ -1,4 +1,4 @@
 // RUN: not %clang_cc1 -emit-llvm -o %t.doesnotexist/somename %s 2> %t
-// RUN: FileCheck -check-prefix=OUTPUTFAIL -input-file=%t %s
+// RUN: FileCheck -check-prefix=OUTPUTFAIL -DMSG=%errc_ENOENT -input-file=%t %s
 
-// OUTPUTFAIL: error: unable to open output file '{{.*}}doesnotexist{{.}}somename': '{{[nN]}}o such file or directory'
+// OUTPUTFAIL: error: unable to open output file '{{.*}}doesnotexist{{.}}somename': '[[MSG]]'
diff --git a/clang/test/Frontend/stats-file.c b/clang/test/Frontend/stats-file.c
--- a/clang/test/Frontend/stats-file.c
+++ b/clang/test/Frontend/stats-file.c
@@ -4,5 +4,5 @@
 //  ... here come some json values ...
 // CHECK: }
 
-// RUN: %clang_cc1 -emit-llvm -o %t -stats-file=%t.doesnotexist/bla %s 2>&1 | FileCheck -check-prefix=OUTPUTFAIL %s
-// OUTPUTFAIL: warning: unable to open statistics output file '{{.*}}doesnotexist{{.}}bla': '{{[Nn]}}o such file or directory'
+// RUN: %clang_cc1 -emit-llvm -o %t -stats-file=%t.doesnotexist/bla %s 2>&1 | FileCheck -DMSG=%errc_ENOENT -check-prefix=OUTPUTFAIL %s
+// OUTPUTFAIL: warning: unable to open statistics output file '{{.*}}doesnotexist{{.}}bla': '[[MSG]]'
diff --git a/lld/test/ELF/basic.s b/lld/test/ELF/basic.s
--- a/lld/test/ELF/basic.s
+++ b/lld/test/ELF/basic.s
@@ -219,8 +219,8 @@
 # INVRSP: invalid response file quoting: patatino
 
 # RUN: not ld.lld %t.foo -o /dev/null 2>&1 | \
-# RUN:  FileCheck --check-prefix=MISSING %s
-# MISSING: cannot open {{.*}}.foo: {{[Nn]}}o such file or directory
+# RUN:  FileCheck -DMSG=%errc_ENOENT --check-prefix=MISSING %s
+# MISSING: cannot open {{.*}}.foo: [[MSG]]
 
 # RUN: not ld.lld -o /dev/null 2>&1 | \
 # RUN:  FileCheck --check-prefix=NO_INPUT %s
diff --git a/llvm/docs/TestingGuide.rst b/llvm/docs/TestingGuide.rst
--- a/llvm/docs/TestingGuide.rst
+++ b/llvm/docs/TestingGuide.rst
@@ -537,6 +537,16 @@
 
    Example: ``%:s: C\Desktop Files\foo_test.s.tmp``
 
+``%errc_<ERRCODE>``
+
+ Some error messages may be substituted to allow different spellings
+ based on the host platform.
+
+   The following error codes are supported: ENOENT, EISDIR.
+
+   Example: ``Linux %errc_ENOENT: No such file or directory``
+
+   Example: ``Windows %errc_ENOENT: no such file or directory``
 
 **LLVM-specific substitutions:**
 
diff --git a/llvm/test/Object/archive-extract.test b/llvm/test/Object/archive-extract.test
--- a/llvm/test/Object/archive-extract.test
+++ b/llvm/test/Object/archive-extract.test
@@ -57,5 +57,5 @@
 RUN: llvm-ar p %p/Inputs/thin.a evenlen | FileCheck %s --check-prefix=EVENLEN
 EVENLEN: evenlen
 
-RUN: not llvm-ar p %p/Inputs/thin-path.a t/test2.o 2>&1 | FileCheck %s --check-prefix=MISSING
-MISSING: error: {{N|n}}o such file or directory
+RUN: not llvm-ar p %p/Inputs/thin-path.a t/test2.o 2>&1 | FileCheck %s --DMSG=%errc_ENOENT --check-prefix=MISSING
+MISSING: error: [[MSG]]
diff --git a/llvm/test/Object/directory.ll b/llvm/test/Object/directory.ll
--- a/llvm/test/Object/directory.ll
+++ b/llvm/test/Object/directory.ll
@@ -1,6 +1,6 @@
 ;RUN: rm -rf %t && mkdir -p %t
-;RUN: not llvm-ar r %t/test.a . 2>&1 | FileCheck %s
-;CHECK: .: {{I|i}}s a directory
+;RUN: not llvm-ar r %t/test.a . 2>&1 | FileCheck -DMSG=%errc_EISDIR %s
+;CHECK: .: [[MSG]]
 
 ;RUN: rm -f %t/test.a
 ;RUN: touch %t/a-very-long-file-name
diff --git a/llvm/test/tools/llvm-ar/move.test b/llvm/test/tools/llvm-ar/move.test
--- a/llvm/test/tools/llvm-ar/move.test
+++ b/llvm/test/tools/llvm-ar/move.test
@@ -82,9 +82,9 @@
 ## Member does not exist:
 # RUN: llvm-ar rc %t/missing.a %t/1.o %t/2.o %t/3.o
 # RUN: not llvm-ar m %t/missing.a %t/missing.txt 2>&1 \
-# RUN:   | FileCheck %s --check-prefix=MISSING-FILE -DFILE=%t/missing.txt
+# RUN:   | FileCheck %s --check-prefix=MISSING-FILE -DFILE=%t/missing.txt -DMSG=%errc_ENOENT
 
-# MISSING-FILE: error: [[FILE]]: {{[nN]}}o such file or directory
+# MISSING-FILE: error: [[FILE]]: [[MSG]]
 
 --- !ELF
 FileHeader:
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
@@ -345,6 +345,17 @@
         self.config.substitutions.extend(substitutions)
         return True
 
+    def add_err_msg_substitutions(self):
+        if (sys.platform == 'zos'):
+            self.config.substitutions.append(('%errc_ENOENT', '\'EDC5129I No such file or directory.\''))
+            self.config.substitutions.append(('%errc_EISDIR', '\'EDC5123I Is a directory.\''))
+        elif (sys.platform == 'win32'):
+            self.config.substitutions.append(('%errc_ENOENT', '\'no such file or directory\''))
+            self.config.substitutions.append(('%errc_EISDIR', '\'is a directory\''))
+        else:
+            self.config.substitutions.append(('%errc_ENOENT', '\'No such file or directory\''))
+            self.config.substitutions.append(('%errc_EISDIR', '\'Is a directory\''))
+
     def use_default_substitutions(self):
         tool_patterns = [
             ToolSubst('FileCheck', unresolved='fatal'),
@@ -358,6 +369,8 @@
         self.add_tool_substitutions(
             tool_patterns, [self.config.llvm_tools_dir])
 
+        self.add_err_msg_substitutions()
+
     def use_llvm_tool(self, name, search_env=None, required=False, quiet=False):
         """Find the executable program 'name', optionally using the specified
         environment variable as an override before searching the