diff --git a/llvm/include/llvm/MC/StringTableBuilder.h b/llvm/include/llvm/MC/StringTableBuilder.h
--- a/llvm/include/llvm/MC/StringTableBuilder.h
+++ b/llvm/include/llvm/MC/StringTableBuilder.h
@@ -37,6 +37,7 @@
 private:
   DenseMap<CachedHashStringRef, size_t> StringIndexMap;
   size_t Size = 0;
+  size_t PaddingSize = 0;
   Kind K;
   unsigned Alignment;
   bool Finalized = false;
@@ -80,6 +81,7 @@
   }
 
   size_t getSize() const { return Size; }
+  void setPaddingSize(size_t Pad) { PaddingSize = Pad; }
   void clear();
 
   void write(raw_ostream &OS) const;
diff --git a/llvm/include/llvm/ObjectYAML/XCOFFYAML.h b/llvm/include/llvm/ObjectYAML/XCOFFYAML.h
--- a/llvm/include/llvm/ObjectYAML/XCOFFYAML.h
+++ b/llvm/include/llvm/ObjectYAML/XCOFFYAML.h
@@ -59,10 +59,17 @@
   uint8_t NumberOfAuxEntries;
 };
 
+struct StringTable {
+  bool Suppressed;
+  uint32_t Length;
+  std::vector<StringRef> Strings;
+};
+
 struct Object {
   FileHeader Header;
   std::vector<Section> Sections;
   std::vector<Symbol> Symbols;
+  StringTable StrTbl;
   Object();
 };
 } // namespace XCOFFYAML
@@ -100,6 +107,10 @@
   static void mapping(IO &IO, XCOFFYAML::Section &Sec);
 };
 
+template <> struct MappingTraits<XCOFFYAML::StringTable> {
+  static void mapping(IO &IO, XCOFFYAML::StringTable &Str);
+};
+
 template <> struct MappingTraits<XCOFFYAML::Object> {
   static void mapping(IO &IO, XCOFFYAML::Object &Obj);
 };
diff --git a/llvm/lib/MC/StringTableBuilder.cpp b/llvm/lib/MC/StringTableBuilder.cpp
--- a/llvm/lib/MC/StringTableBuilder.cpp
+++ b/llvm/lib/MC/StringTableBuilder.cpp
@@ -167,6 +167,9 @@
     }
   }
 
+  Size += PaddingSize;
+  Size = alignTo(Size, Alignment);
+
   if (K == MachO || K == MachOLinked)
     Size = alignTo(Size, 4); // Pad to multiple of 4.
   if (K == MachO64 || K == MachO64Linked)
diff --git a/llvm/lib/ObjectYAML/XCOFFEmitter.cpp b/llvm/lib/ObjectYAML/XCOFFEmitter.cpp
--- a/llvm/lib/ObjectYAML/XCOFFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/XCOFFEmitter.cpp
@@ -14,12 +14,12 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/BinaryFormat/XCOFF.h"
 #include "llvm/MC/StringTableBuilder.h"
-#include "llvm/Object/XCOFFObjectFile.h"
 #include "llvm/ObjectYAML/ObjectYAML.h"
+#include "llvm/Object/XCOFFObjectFile.h"
 #include "llvm/ObjectYAML/yaml2obj.h"
 #include "llvm/Support/EndianStream.h"
-#include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/LEB128.h"
+#include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 
@@ -33,7 +33,7 @@
 public:
   XCOFFWriter(XCOFFYAML::Object &Obj, raw_ostream &OS, yaml::ErrorHandler EH)
       : Obj(Obj), W(OS, support::big), ErrHandler(EH),
-        Strings(StringTableBuilder::XCOFF) {
+        StrTbl(StringTableBuilder::XCOFF) {
     Is64Bit = Obj.Header.Magic == (llvm::yaml::Hex16)XCOFF::XCOFF64;
   }
   bool writeXCOFF();
@@ -43,6 +43,7 @@
   bool initFileHeader(uint64_t CurrentOffset);
   bool initSectionHeader(uint64_t &CurrentOffset);
   bool initRelocations(uint64_t &CurrentOffset);
+  bool initStringTable();
   bool assignAddressesAndIndices();
   void writeFileHeader();
   void writeSectionHeader();
@@ -54,7 +55,7 @@
   bool Is64Bit = false;
   support::endian::Writer W;
   yaml::ErrorHandler ErrHandler;
-  StringTableBuilder Strings;
+  StringTableBuilder StrTbl;
   uint64_t StartOffset;
   // Map the section name to its corrresponding section index.
   DenseMap<StringRef, int16_t> SectionIndexMap = {
@@ -140,20 +141,53 @@
   return initRelocations(CurrentOffset);
 }
 
+bool XCOFFWriter::initStringTable() {
+  StrTbl.clear();
+
+  // All specified strings should be added to the string table.
+  for (StringRef StringEnt : Obj.StrTbl.Strings)
+    StrTbl.add(StringEnt);
+
+  size_t NumOfStrings = Obj.StrTbl.Strings.size();
+  size_t StrTblIdx = 0;
+  for (XCOFFYAML::Symbol &YamlSym : Obj.Symbols) {
+    if (nameShouldBeInStringTable(YamlSym.SymbolName)) {
+      if (StrTblIdx < NumOfStrings) {
+        // Overwrite the symbol name with the specified string.
+        YamlSym.SymbolName = Obj.StrTbl.Strings[StrTblIdx];
+        ++StrTblIdx;
+      } else
+        // Unoverwritten names are still stored in the string table.
+        StrTbl.add(YamlSym.SymbolName);
+    }
+  }
+
+  // Set the string table length field with a custom value, if specified.
+  if (Obj.StrTbl.Length) {
+    size_t StrTblSize = StrTbl.getSize();
+    if (Obj.StrTbl.Length < StrTblSize) {
+      ErrHandler("specified length (" + Twine(Obj.StrTbl.Length) +
+                 ") is less than the content size (" + Twine(StrTblSize) + ")");
+      return false;
+    }
+    // Add zeros as padding after strings.
+    size_t PaddingSize = Obj.StrTbl.Length - StrTblSize;
+    StrTbl.setPaddingSize(PaddingSize);
+  }
+
+  StrTbl.finalize();
+  return true;
+}
+
 bool XCOFFWriter::initFileHeader(uint64_t CurrentOffset) {
   // The default format of the object file is XCOFF32.
   InitFileHdr.Magic = XCOFF::XCOFF32;
   InitFileHdr.NumberOfSections = Obj.Sections.size();
   InitFileHdr.NumberOfSymTableEntries = Obj.Symbols.size();
 
-  for (const XCOFFYAML::Symbol &YamlSym : Obj.Symbols) {
+  for (const XCOFFYAML::Symbol &YamlSym : Obj.Symbols)
     // Add the number of auxiliary symbols to the total number.
     InitFileHdr.NumberOfSymTableEntries += YamlSym.NumberOfAuxEntries;
-    if (nameShouldBeInStringTable(YamlSym.SymbolName))
-      Strings.add(YamlSym.SymbolName);
-  }
-  // Finalize the string table.
-  Strings.finalize();
 
   // Calculate SymbolTableOffset for the file header.
   if (InitFileHdr.NumberOfSymTableEntries) {
@@ -171,7 +205,6 @@
 }
 
 bool XCOFFWriter::assignAddressesAndIndices() {
-  Strings.clear();
   uint64_t FileHdrSize =
       Is64Bit ? XCOFF::FileHeaderSize64 : XCOFF::FileHeaderSize32;
   uint64_t SecHdrSize =
@@ -182,8 +215,13 @@
   // Calculate section header info.
   if (!initSectionHeader(CurrentOffset))
     return false;
+
   // Calculate file header info.
-  return initFileHeader(CurrentOffset);
+  if (!initFileHeader(CurrentOffset))
+    return false;
+
+  // Initialize the string table.
+  return initStringTable();
 }
 
 void XCOFFWriter::writeFileHeader() {
@@ -309,13 +347,13 @@
   for (const XCOFFYAML::Symbol &YamlSym : Obj.Symbols) {
     if (Is64Bit) {
       W.write<uint64_t>(YamlSym.Value);
-      W.write<uint32_t>(Strings.getOffset(YamlSym.SymbolName));
+      W.write<uint32_t>(StrTbl.getOffset(YamlSym.SymbolName));
     } else {
       if (nameShouldBeInStringTable(YamlSym.SymbolName)) {
         // For XCOFF32: A value of 0 indicates that the symbol name is in the
         // string table.
         W.write<int32_t>(0);
-        W.write<uint32_t>(Strings.getOffset(YamlSym.SymbolName));
+        W.write<uint32_t>(StrTbl.getOffset(YamlSym.SymbolName));
       } else {
         writeName(YamlSym.SymbolName, W);
       }
@@ -355,8 +393,8 @@
   if (!Obj.Symbols.empty() && !writeSymbols())
     return false;
   // Write the string table.
-  if (Strings.getSize() > 4)
-    Strings.write(W.OS);
+  if (StrTbl.getSize() > 4 && !Obj.StrTbl.Suppressed)
+    StrTbl.write(W.OS);
   return true;
 }
 
diff --git a/llvm/lib/ObjectYAML/XCOFFYAML.cpp b/llvm/lib/ObjectYAML/XCOFFYAML.cpp
--- a/llvm/lib/ObjectYAML/XCOFFYAML.cpp
+++ b/llvm/lib/ObjectYAML/XCOFFYAML.cpp
@@ -143,7 +143,7 @@
 }
 
 void MappingTraits<XCOFFYAML::Symbol>::mapping(IO &IO, XCOFFYAML::Symbol &S) {
-  IO.mapRequired("Name", S.SymbolName);
+  IO.mapOptional("Name", S.SymbolName);
   IO.mapOptional("Value", S.Value);
   IO.mapOptional("Section", S.SectionName);
   IO.mapOptional("Type", S.Type);
@@ -151,11 +151,18 @@
   IO.mapOptional("NumberOfAuxEntries", S.NumberOfAuxEntries);
 }
 
+void MappingTraits<XCOFFYAML::StringTable>::mapping(IO &IO, XCOFFYAML::StringTable &Str) {
+  IO.mapOptional("Suppress", Str.Suppressed);
+  IO.mapOptional("Length", Str.Length);
+  IO.mapOptional("Strings", Str.Strings);
+}
+
 void MappingTraits<XCOFFYAML::Object>::mapping(IO &IO, XCOFFYAML::Object &Obj) {
   IO.mapTag("!XCOFF", true);
   IO.mapRequired("FileHeader", Obj.Header);
   IO.mapOptional("Sections", Obj.Sections);
   IO.mapOptional("Symbols", Obj.Symbols);
+  IO.mapOptional("StringTable", Obj.StrTbl);
 }
 
 } // namespace yaml
diff --git a/llvm/test/tools/obj2yaml/XCOFF/aix.yaml b/llvm/test/tools/obj2yaml/XCOFF/aix.yaml
--- a/llvm/test/tools/obj2yaml/XCOFF/aix.yaml
+++ b/llvm/test/tools/obj2yaml/XCOFF/aix.yaml
@@ -77,4 +77,5 @@
 # CHECK-NEXT:     Type:      0x0
 # CHECK-NEXT:     StorageClass:    C_HIDEXT
 # CHECK-NEXT:     NumberOfAuxEntries: 1
-# CHECK-NEXT: ...
+
+## TODO: Dump the string table.
diff --git a/llvm/test/tools/yaml2obj/XCOFF/string-table.yaml b/llvm/test/tools/yaml2obj/XCOFF/string-table.yaml
--- a/llvm/test/tools/yaml2obj/XCOFF/string-table.yaml
+++ b/llvm/test/tools/yaml2obj/XCOFF/string-table.yaml
@@ -0,0 +1,232 @@
+## Check that yaml2obj is able to customize the string table.
+## `Length`, `Strings` and/or `Suppress` can be specified in YAML.
+## Here we test the behaviour in various cases.
+
+## Case 1: when no `Length` or `Strings` is specified for a string table,
+##         yaml2obj writes the default content (i.e. long symbol names in
+##         XCOFF32 or any symbol names in XCOFF64).
+# RUN: yaml2obj --docnum=1 %s -DSYMNAME='nameInStrTbl' -o %t1
+# RUN: llvm-readobj %t1 --string-table | FileCheck %s --check-prefix=CASE1
+
+# CASE1:      StringTable {
+# CASE1-NEXT:   Length: 17
+# CASE1-NEXT:   [     4]   nameInStrTbl
+# CASE1-NEXT: }
+
+--- !XCOFF
+FileHeader:
+  MagicNumber: 0x1DF
+Symbols:
+  - Name: [[SYMNAME=<none>]]
+StringTable:
+  Suppress: [[SUPPRESS=false]]
+  Length: [[STRTABSIZE=0]]
+
+## We can specify `Length` only when the length value is equal to or greater 
+## than the content size. For greater cases, zeros are added as padding. 
+## Case 2-4 are trying to check this function. Notice that we do not specify 
+## `Strings` in these cases.
+
+## Case 2: produce a string table with a specified `Length`. In this case,
+##         there is no default content and the content is filled with zeroes.
+# RUN: yaml2obj --docnum=1 %s -DSTRTABSIZE=20 -o %t2
+# RUN: llvm-readobj %t2 -s --string-table | FileCheck %s --check-prefix=CASE2
+
+# CASE2:      StringTable {
+# CASE2-NEXT:   Length: 20
+# CASE2-NEXT: }
+
+## Case 3: if the value of `Length` is greater than the content size, yaml2obj
+##         adds zeros as padding after the default content.
+# RUN: yaml2obj --docnum=1 %s -DSYMNAME='nameInStrTbl' -DSTRTABSIZE=20 -o %t3
+# RUN: llvm-readobj %t3 --string-table | FileCheck %s --check-prefix=CASE3
+
+# CASE3:      StringTable {
+# CASE3-NEXT:   Length: 20
+# CASE3-NEXT:   [     4]   nameInStrTbl
+# CASE3-NEXT: }
+
+## Case 4: an error is reported when the value of "Length" is less than the
+##         content size.
+# RUN: not yaml2obj --docnum=1 %s -DSYMNAME='nameInStrTbl' -DSTRTABSIZE=10 \
+# RUN:   -o %t4 2>&1 | FileCheck %s --check-prefix=CASE4
+
+# CASE4: yaml2obj: error: specified length (10) is less than the content size (17)
+
+## We can specify `Strings` for a string table. Default contents (ie. symbol 
+## names in string table) will be overwritten by specified values. Case 5-7
+## are trying to check this function. Notice that we do not specify `Length`
+## in those cases, and the length value is implicitly generated.
+
+## Case 5: produce a string table with specified `Strings` directly. In this
+##         case, there is no default content.
+# RUN: yaml2obj --docnum=2 %s -o %t5
+# RUN: llvm-readobj %t5 --string-table | FileCheck %s --check-prefix=CASE5
+
+# CASE5:      StringTable {
+# CASE5-NEXT:   Length: 8
+# CASE5-NEXT:   [     4]   b
+# CASE5-NEXT:   [     6]   a
+# CASE5-NEXT: }
+
+--- !XCOFF
+FileHeader:
+  MagicNumber: 0x1DF
+Symbols:
+  - Name: [[SYMNAME=<none>]]
+  - Name: [[SYMNAME2=<none>]]
+  - Name: [[SYMNAME3=<none>]]
+StringTable:
+  Suppress: [[SUPPRESS=false]]
+  Length: [[STRTABSIZE=0]]
+  Strings:
+    - a
+    - b
+
+## Case 6: if the number of `Strings` is greater than default strings, all
+##         default strings will be overwritten by specified ones.
+# RUN: yaml2obj --docnum=2 %s -DSYMNAME='nameInStrTbl' -o %t6
+# RUN: llvm-readobj %t6 -s --string-table | FileCheck %s --check-prefix=CASE6
+
+# CASE6:      Symbols [
+# CASE6-NEXT:   Symbol {
+# CASE6-NEXT:     Index: 0
+# CASE6-NEXT:     Name: a
+# CASE6-NEXT:     Value: 0x0
+# CASE6-NEXT:     Section: N_UNDEF
+# CASE6-NEXT:     Type: 0x0
+# CASE6-NEXT:     StorageClass: C_NULL (0x0)
+# CASE6-NEXT:     NumberOfAuxEntries: 0
+# CASE6-NEXT:   }
+# CASE6-NEXT:   Symbol {
+# CASE6-NEXT:     Index: 1
+# CASE6-NEXT:     Name: <none>
+# CASE6-NEXT:     Value: 0x0
+# CASE6-NEXT:     Section: N_UNDEF
+# CASE6-NEXT:     Type: 0x0
+# CASE6-NEXT:     StorageClass: C_NULL (0x0)
+# CASE6-NEXT:     NumberOfAuxEntries: 0
+# CASE6-NEXT:   }
+# CASE6-NEXT:   Symbol {
+# CASE6-NEXT:     Index: 2
+# CASE6-NEXT:     Name: <none>
+# CASE6-NEXT:     Value: 0x0
+# CASE6-NEXT:     Section: N_UNDEF
+# CASE6-NEXT:     Type: 0x0
+# CASE6-NEXT:     StorageClass: C_NULL (0x0)
+# CASE6-NEXT:     NumberOfAuxEntries: 0
+# CASE6-NEXT:   }
+# CASE6-NEXT: ]
+# CASE6-NEXT: StringTable {
+# CASE6-NEXT:   Length: 8
+# CASE6-NEXT:   [     4]   b
+# CASE6-NEXT:   [     6]   a
+# CASE6-NEXT: }
+
+## Case 7: if the number of `Strings` is less than default strings, default
+##         strings will be partially overwritten by specified ones, and the
+##         unoverwritten strings will still be stored after specified strings
+##         in the string table.
+# RUN: yaml2obj --docnum=2 %s -DSYMNAME='nameInStrTbl' \
+# RUN:   -DSYMNAME2='name2InStrTbl' -DSYMNAME3='name3InStrTbl' -o %t7
+# RUN: llvm-readobj %t7 -s --string-table | FileCheck %s --check-prefix=CASE7
+
+# CASE7:      Symbols [
+# CASE7-NEXT:   Symbol {
+# CASE7-NEXT:     Index: 0
+# CASE7-NEXT:     Name: a
+# CASE7-NEXT:     Value: 0x0
+# CASE7-NEXT:     Section: N_UNDEF
+# CASE7-NEXT:     Type: 0x0
+# CASE7-NEXT:     StorageClass: C_NULL (0x0)
+# CASE7-NEXT:     NumberOfAuxEntries: 0
+# CASE7-NEXT:   }
+# CASE7-NEXT:   Symbol {
+# CASE7-NEXT:     Index: 1
+# CASE7-NEXT:     Name: b
+# CASE7-NEXT:     Value: 0x0
+# CASE7-NEXT:     Section: N_UNDEF
+# CASE7-NEXT:     Type: 0x0
+# CASE7-NEXT:     StorageClass: C_NULL (0x0)
+# CASE7-NEXT:     NumberOfAuxEntries: 0
+# CASE7-NEXT:   }
+# CASE7-NEXT:   Symbol {
+# CASE7-NEXT:     Index: 2
+# CASE7-NEXT:     Name: name3InStrTbl
+# CASE7-NEXT:     Value: 0x0
+# CASE7-NEXT:     Section: N_UNDEF
+# CASE7-NEXT:     Type: 0x0
+# CASE7-NEXT:     StorageClass: C_NULL (0x0)
+# CASE7-NEXT:     NumberOfAuxEntries: 0
+# CASE7-NEXT:   }
+# CASE7-NEXT: ]
+# CASE7-NEXT: StringTable {
+# CASE7-NEXT:   Length: 22
+# CASE7-NEXT:   [     4]   name3InStrTbl  
+# CASE7-NEXT:   [    12]   b
+# CASE7-NEXT:   [    14]   a
+# CASE7-NEXT: }
+
+## We can specify both `Length` and `Strings` when the length value is equal
+## to or greater than the content size. Case 8-10 are trying to check this.
+
+## Case 8: produce a string table with specified `Length` and `Strings` when
+##         the length value is greater than the size of specified strings.
+##         In this case, there is no default content.
+# RUN: yaml2obj --docnum=2 %s -DSTRTABSIZE=20 -o %t8
+# RUN: llvm-readobj %t8 --string-table | FileCheck %s --check-prefix=CASE8
+
+# CASE8:      StringTable {
+# CASE8-NEXT:   Length: 20
+# CASE8-NEXT:   [     4]   b
+# CASE8-NEXT:   [     6]   a
+# CASE8-NEXT: }
+
+## Case 9: for a string table with default contents, we can specify `Length` 
+##         and `Strings` when the length size is greater than the final
+##         content size.
+# RUN: yaml2obj --docnum=2 %s -DSTRTABSIZE=30 -DSYMNAME='nameInStrTbl' \
+# RUN:   -DSYMNAME2='name2InStrTbl' -DSYMNAME3='name3InStrTbl' -o %t9
+# RUN: llvm-readobj %t9 --string-table | FileCheck %s --check-prefix=CASE9
+
+# CASE9:      StringTable {
+# CASE9-NEXT:   Length: 30
+# CASE9-NEXT:   [     4]   name3InStrTbl
+# CASE9-NEXT:   [    12]   b
+# CASE9-NEXT:   [    14]   a
+# CASE9-NEXT: }
+
+## Case 10: an error will be reported when the value of `Length` is less than
+##          the final content size. None of `Length`, `Strings` or default
+##          contents is empty in this case.
+# RUN: not yaml2obj --docnum=2 %s  -DSTRTABSIZE=10 -DSYMNAME='nameInStrTbl' \
+# RUN:   -DSYMNAME2='name2InStrTbl' -DSYMNAME3='name3InStrTbl' -o %t9 2>&1 \
+# RUN:   | FileCheck %s --check-prefix=CASE10
+
+# CASE10: yaml2obj: error: specified length (10) is less than the content size (22)
+
+## We can set `Suppress` as true to suppress the emission of string table.
+## Case 11-13 are trying to check this.
+
+## Case 11: both `Suppress` and `Length` are specified.
+# RUN: yaml2obj --docnum=1 %s -DSTRTABSIZE=10 -DSUPPRESS=true -o %t11
+# RUN: llvm-readobj %t11 --string-table | FileCheck %s --check-prefix=CASE11
+
+# CASE11:      StringTable {
+# CASE11-NEXT:   Length: 0
+# CASE11-NEXT: }
+
+## Case 12: both `Suppress` and `Strings` are specified.
+# RUN: yaml2obj --docnum=2 %s -DSUPPRESS=true -o %t12
+# RUN: llvm-readobj %t12 --string-table | FileCheck %s --check-prefix=CASE12
+
+# CASE12:      StringTable {
+# CASE12-NEXT:   Length: 0
+# CASE12-NEXT: }
+
+## Case 13: for a string table with default contents, `Suppress` of true triggers 
+##          an error (since symbol names cannot be found from the string table).
+# RUN: yaml2obj --docnum=1 %s -DSYMNAME='nameInStrTbl' -DSUPPRESS=true -o %t13
+# RUN: not llvm-readobj -s 2>&1 %t13 | FileCheck -DFILE=%t13 %s --check-prefix=CASE13
+
+# CASE13: llvm-readobj: error: '[[FILE]]': Bad offset for string table entry