diff --git a/llvm/lib/Object/WindowsMachineFlag.cpp b/llvm/lib/Object/WindowsMachineFlag.cpp
index b9f818775768a..caf357e8c136f 100644
--- a/llvm/lib/Object/WindowsMachineFlag.cpp
+++ b/llvm/lib/Object/WindowsMachineFlag.cpp
@@ -21,6 +21,7 @@ using namespace llvm;
 
 // Returns /machine's value.
 COFF::MachineTypes llvm::getMachineType(StringRef S) {
+  // Flags must be a superset of Microsoft lib.exe /machine flags.
   return StringSwitch<COFF::MachineTypes>(S.lower())
       .Cases("x64", "amd64", COFF::IMAGE_FILE_MACHINE_AMD64)
       .Cases("x86", "i386", COFF::IMAGE_FILE_MACHINE_I386)
@@ -28,6 +29,7 @@ COFF::MachineTypes llvm::getMachineType(StringRef S) {
       .Case("arm64", COFF::IMAGE_FILE_MACHINE_ARM64)
       .Case("arm64ec", COFF::IMAGE_FILE_MACHINE_ARM64EC)
       .Case("arm64x", COFF::IMAGE_FILE_MACHINE_ARM64X)
+      .Case("mips", COFF::IMAGE_FILE_MACHINE_R4000)
       .Default(COFF::IMAGE_FILE_MACHINE_UNKNOWN);
 }
 
diff --git a/llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp b/llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp
index 138d9fc7f1d7f..6ce06b434b2c0 100644
--- a/llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp
+++ b/llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp
@@ -171,6 +171,7 @@ static Expected<COFF::MachineTypes> getCOFFFileMachine(MemoryBufferRef MB) {
   uint16_t Machine = (*Obj)->getMachine();
   if (Machine != COFF::IMAGE_FILE_MACHINE_I386 &&
       Machine != COFF::IMAGE_FILE_MACHINE_AMD64 &&
+      Machine != COFF::IMAGE_FILE_MACHINE_R4000 &&
       Machine != COFF::IMAGE_FILE_MACHINE_ARMNT && !COFF::isAnyArm64(Machine)) {
     return createStringError(inconvertibleErrorCode(),
                              "unknown machine: " + std::to_string(Machine));
@@ -195,6 +196,8 @@ static Expected<COFF::MachineTypes> getBitcodeFileMachine(MemoryBufferRef MB) {
   case Triple::aarch64:
     return T.isWindowsArm64EC() ? COFF::IMAGE_FILE_MACHINE_ARM64EC
                                 : COFF::IMAGE_FILE_MACHINE_ARM64;
+  case Triple::mipsel:
+    return COFF::IMAGE_FILE_MACHINE_R4000;
   default:
     return createStringError(inconvertibleErrorCode(),
                              "unknown arch in target triple: " + *TripleStr);
diff --git a/llvm/test/tools/llvm-lib/Inputs/mips.ll b/llvm/test/tools/llvm-lib/Inputs/mips.ll
new file mode 100644
index 0000000000000..dd0f8338cfa97
--- /dev/null
+++ b/llvm/test/tools/llvm-lib/Inputs/mips.ll
@@ -0,0 +1,7 @@
+target triple = "mipsel-windows-coff"
+
+; Function Attrs: noinline nounwind optnone
+define dso_local void @"?f@@YAXXZ"() #0 {
+entry:
+  ret void
+}
diff --git a/llvm/test/tools/llvm-lib/infer-machine.test b/llvm/test/tools/llvm-lib/infer-machine.test
new file mode 100644
index 0000000000000..c1399c617af40
--- /dev/null
+++ b/llvm/test/tools/llvm-lib/infer-machine.test
@@ -0,0 +1,19 @@
+RUN: rm -rf %t && mkdir -p %t
+
+RUN: llc -mtriple=i386-windows-coff -filetype=obj -o %t/i386.obj %S/Inputs/i386.ll
+RUN: llvm-as %S/Inputs/i386.ll -o %t/i386.bc
+RUN: llvm-lib %t/i386.obj %t/i386.bc /out:%t/i386.lib
+RUN: llvm-objdump -h %t/i386.lib | FileCheck %s --check-prefix=I386
+I386: file format coff-i386
+
+RUN: llc -mtriple=x86_64-windows-coff -filetype=obj -o %t/x86_64.obj %S/Inputs/x86_64.ll
+RUN: llvm-as %S/Inputs/x86_64.ll -o %t/x86_64.bc
+RUN: llvm-lib %t/x86_64.obj %t/x86_64.bc /out:%t/x86_64.lib
+RUN: llvm-objdump -h %t/x86_64.lib | FileCheck %s --check-prefix=X86_64
+X86_64: file format coff-x86-64
+
+RUN: llc -mtriple=mipsel-windows-coff -filetype=obj -o %t/mips.obj %S/Inputs/mips.ll
+RUN: llvm-as %S/Inputs/mips.ll -o %t/mips.bc
+RUN: llvm-lib %t/mips.obj %t/mips.bc /out:%t/mips.lib
+RUN: llvm-objdump -h %t/mips.lib | FileCheck %s --check-prefix=MIPS
+MIPS: file format coff-mips
diff --git a/llvm/test/tools/llvm-lib/machine-opt.test b/llvm/test/tools/llvm-lib/machine-opt.test
new file mode 100644
index 0000000000000..e5ade82c2f0a6
--- /dev/null
+++ b/llvm/test/tools/llvm-lib/machine-opt.test
@@ -0,0 +1,13 @@
+RUN: rm -f %t.lib
+
+RUN: llvm-lib /out:%t.lib /machine:i386 2>&1 | FileCheck --check-prefix=EMPTYWARN %s
+RUN: llvm-lib /out:%t.lib /machine:amd64 2>&1 | FileCheck --check-prefix=EMPTYWARN %s
+
+RUN: llvm-lib /out:%t.lib /machine:mips 2>&1 | FileCheck --check-prefix=EMPTYWARN %s
+
+RUN: llvm-lib /out:%t.lib /machine:arm 2>&1 | FileCheck --check-prefix=EMPTYWARN %s
+RUN: llvm-lib /out:%t.lib /machine:arm64 2>&1 | FileCheck --check-prefix=EMPTYWARN %s
+RUN: llvm-lib /out:%t.lib /machine:arm64x 2>&1 | FileCheck --check-prefix=EMPTYWARN %s
+
+EMPTYWARN: warning: no input files, not writing output file
+