diff --git a/llvm/lib/Target/Mips/MipsLegalizerInfo.cpp b/llvm/lib/Target/Mips/MipsLegalizerInfo.cpp
--- a/llvm/lib/Target/Mips/MipsLegalizerInfo.cpp
+++ b/llvm/lib/Target/Mips/MipsLegalizerInfo.cpp
@@ -54,6 +54,10 @@
                                {s32, p0, 16, 8}})
       .minScalar(0, s32);
 
+  getActionDefinitionsBuilder({G_ZEXT, G_SEXT})
+      .legalIf([](const LegalityQuery &Query) { return false; })
+      .maxScalar(0, s32);
+
   getActionDefinitionsBuilder(G_TRUNC)
       .legalIf([](const LegalityQuery &Query) { return false; })
       .maxScalar(1, s32);
diff --git a/llvm/test/CodeGen/Mips/GlobalISel/legalizer/zext_and_sext.mir b/llvm/test/CodeGen/Mips/GlobalISel/legalizer/zext_and_sext.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/Mips/GlobalISel/legalizer/zext_and_sext.mir
@@ -0,0 +1,61 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -O0 -mtriple=mipsel-linux-gnu -run-pass=legalizer -verify-machineinstrs %s -o - | FileCheck %s -check-prefixes=MIPS32
+--- |
+
+  define void @zext() {entry: ret void}
+  define void @sext() {entry: ret void}
+
+...
+---
+name:            zext
+alignment:       2
+tracksRegLiveness: true
+body:             |
+  bb.1.entry:
+    liveins: $a0
+
+    ; MIPS32-LABEL: name: zext
+    ; MIPS32: liveins: $a0
+    ; MIPS32: [[COPY:%[0-9]+]]:_(s32) = COPY $a0
+    ; MIPS32: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
+    ; MIPS32: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[COPY]](s32), [[C]](s32)
+    ; MIPS32: [[UV:%[0-9]+]]:_(s32), [[UV1:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[MV]](s64)
+    ; MIPS32: $v0 = COPY [[UV]](s32)
+    ; MIPS32: $v1 = COPY [[UV1]](s32)
+    ; MIPS32: RetRA implicit $v0, implicit $v1
+    %0:_(s32) = COPY $a0
+    %1:_(s64) = G_ZEXT %0(s32)
+    %2:_(s32), %3:_(s32) = G_UNMERGE_VALUES %1(s64)
+    $v0 = COPY %2(s32)
+    $v1 = COPY %3(s32)
+    RetRA implicit $v0, implicit $v1
+
+...
+---
+name:            sext
+alignment:       2
+tracksRegLiveness: true
+body:             |
+  bb.1.entry:
+    liveins: $a0
+
+    ; MIPS32-LABEL: name: sext
+    ; MIPS32: liveins: $a0
+    ; MIPS32: [[COPY:%[0-9]+]]:_(s32) = COPY $a0
+    ; MIPS32: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 31
+    ; MIPS32: [[C1:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
+    ; MIPS32: [[COPY1:%[0-9]+]]:_(s32) = COPY [[C]](s32)
+    ; MIPS32: [[ASHR:%[0-9]+]]:_(s32) = G_ASHR [[COPY]], [[COPY1]](s32)
+    ; MIPS32: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[COPY]](s32), [[ASHR]](s32)
+    ; MIPS32: [[UV:%[0-9]+]]:_(s32), [[UV1:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[MV]](s64)
+    ; MIPS32: $v0 = COPY [[UV]](s32)
+    ; MIPS32: $v1 = COPY [[UV1]](s32)
+    ; MIPS32: RetRA implicit $v0, implicit $v1
+    %0:_(s32) = COPY $a0
+    %1:_(s64) = G_SEXT %0(s32)
+    %2:_(s32), %3:_(s32) = G_UNMERGE_VALUES %1(s64)
+    $v0 = COPY %2(s32)
+    $v1 = COPY %3(s32)
+    RetRA implicit $v0, implicit $v1
+
+...
diff --git a/llvm/test/CodeGen/Mips/GlobalISel/llvm-ir/zext_and_sext.ll b/llvm/test/CodeGen/Mips/GlobalISel/llvm-ir/zext_and_sext.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/Mips/GlobalISel/llvm-ir/zext_and_sext.ll
@@ -0,0 +1,27 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc  -O0 -mtriple=mipsel-linux-gnu -global-isel  -verify-machineinstrs %s -o -| FileCheck %s -check-prefixes=MIPS32
+
+define i64 @zext(i32 %x) {
+; MIPS32-LABEL: zext:
+; MIPS32:       # %bb.0: # %entry
+; MIPS32-NEXT:    ori $3, $zero, 0
+; MIPS32-NEXT:    move $2, $4
+; MIPS32-NEXT:    jr $ra
+; MIPS32-NEXT:    nop
+entry:
+  %conv = zext i32 %x to i64
+  ret i64 %conv
+}
+
+define i64 @sext(i32 %x) {
+; MIPS32-LABEL: sext:
+; MIPS32:       # %bb.0: # %entry
+; MIPS32-NEXT:    ori $1, $zero, 31
+; MIPS32-NEXT:    srav $3, $4, $1
+; MIPS32-NEXT:    move $2, $4
+; MIPS32-NEXT:    jr $ra
+; MIPS32-NEXT:    nop
+entry:
+  %conv = sext i32 %x to i64
+  ret i64 %conv
+}
diff --git a/llvm/test/CodeGen/Mips/GlobalISel/regbankselect/zext_and_sext.mir b/llvm/test/CodeGen/Mips/GlobalISel/regbankselect/zext_and_sext.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/Mips/GlobalISel/regbankselect/zext_and_sext.mir
@@ -0,0 +1,64 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -O0 -mtriple=mipsel-linux-gnu -run-pass=regbankselect -verify-machineinstrs %s -o - | FileCheck %s -check-prefixes=MIPS32
+--- |
+
+  define void @zext() {entry: ret void}
+  define void @sext() {entry: ret void}
+
+...
+---
+name:            zext
+alignment:       2
+legalized:       true
+tracksRegLiveness: true
+body:             |
+  bb.1.entry:
+    liveins: $a0
+
+    ; MIPS32-LABEL: name: zext
+    ; MIPS32: liveins: $a0
+    ; MIPS32: [[COPY:%[0-9]+]]:gprb(s32) = COPY $a0
+    ; MIPS32: [[C:%[0-9]+]]:gprb(s32) = G_CONSTANT i32 0
+    ; MIPS32: $v0 = COPY [[COPY]](s32)
+    ; MIPS32: $v1 = COPY [[C]](s32)
+    ; MIPS32: RetRA implicit $v0, implicit $v1
+    %0:_(s32) = COPY $a0
+    %4:_(s32) = G_CONSTANT i32 0
+    %1:_(s64) = G_MERGE_VALUES %0(s32), %4(s32)
+    %2:_(s32), %3:_(s32) = G_UNMERGE_VALUES %1(s64)
+    $v0 = COPY %2(s32)
+    $v1 = COPY %3(s32)
+    RetRA implicit $v0, implicit $v1
+
+...
+---
+name:            sext
+alignment:       2
+legalized:       true
+tracksRegLiveness: true
+body:             |
+  bb.1.entry:
+    liveins: $a0
+
+    ; MIPS32-LABEL: name: sext
+    ; MIPS32: liveins: $a0
+    ; MIPS32: [[COPY:%[0-9]+]]:gprb(s32) = COPY $a0
+    ; MIPS32: [[C:%[0-9]+]]:gprb(s32) = G_CONSTANT i32 31
+    ; MIPS32: [[C1:%[0-9]+]]:gprb(s32) = G_CONSTANT i32 0
+    ; MIPS32: [[COPY1:%[0-9]+]]:gprb(s32) = COPY [[C]](s32)
+    ; MIPS32: [[ASHR:%[0-9]+]]:gprb(s32) = G_ASHR [[COPY]], [[COPY1]](s32)
+    ; MIPS32: $v0 = COPY [[COPY]](s32)
+    ; MIPS32: $v1 = COPY [[ASHR]](s32)
+    ; MIPS32: RetRA implicit $v0, implicit $v1
+    %0:_(s32) = COPY $a0
+    %7:_(s32) = G_CONSTANT i32 31
+    %8:_(s32) = G_CONSTANT i32 0
+    %6:_(s32) = COPY %7(s32)
+    %5:_(s32) = G_ASHR %0, %6(s32)
+    %1:_(s64) = G_MERGE_VALUES %0(s32), %5(s32)
+    %2:_(s32), %3:_(s32) = G_UNMERGE_VALUES %1(s64)
+    $v0 = COPY %2(s32)
+    $v1 = COPY %3(s32)
+    RetRA implicit $v0, implicit $v1
+
+...