diff --git a/flang/.clang-tidy b/flang/.clang-tidy
--- a/flang/.clang-tidy
+++ b/flang/.clang-tidy
@@ -1,2 +1,2 @@
-Checks: '-llvm-include-order,-readability-identifier-naming,-clang-diagnostic-*'
+Checks: '-llvm-include-order,readability-braces-around-statements,-readability-identifier-naming,-clang-diagnostic-*'
 InheritParentConfig: true
diff --git a/flang/docs/C++style.md b/flang/docs/C++style.md
--- a/flang/docs/C++style.md
+++ b/flang/docs/C++style.md
@@ -115,7 +115,10 @@
 align vertically -- they are maintenance problems.
 
 Always wrap the bodies of `if()`, `else`, `while()`, `for()`, `do`, &c.
-with braces, even when the body is a single statement or empty.  The
+with braces, even when the body is a single statement or empty.  Note that this
+diverges from the LLVM coding style.  In parts of the codebase that make heavy
+use of LLVM or MLIR APIs (e.g. the Lower and Optimizer libraries), use the
+LLVM style instead.  The
 opening `{` goes on
 the end of the line, not on the next line.  Functions also put the opening
 `{` after the formal arguments or new-style result type, not on the next
diff --git a/flang/include/flang/Lower/.clang-tidy b/flang/include/flang/Lower/.clang-tidy
--- a/flang/include/flang/Lower/.clang-tidy
+++ b/flang/include/flang/Lower/.clang-tidy
@@ -1,4 +1,4 @@
-Checks: 'readability-identifier-naming,llvm-include-order,clang-diagnostic-*'
+Checks: '-readability-braces-around-statements,readability-identifier-naming,llvm-include-order,clang-diagnostic-*'
 InheritParentConfig: true
 CheckOptions:
   - key:             readability-identifier-naming.MemberCase
diff --git a/flang/include/flang/Optimizer/.clang-tidy b/flang/include/flang/Optimizer/.clang-tidy
--- a/flang/include/flang/Optimizer/.clang-tidy
+++ b/flang/include/flang/Optimizer/.clang-tidy
@@ -1,4 +1,4 @@
-Checks: 'readability-identifier-naming,llvm-include-order,clang-diagnostic-*'
+Checks: '-readability-braces-around-statements,readability-identifier-naming,llvm-include-order,clang-diagnostic-*'
 InheritParentConfig: true
 CheckOptions:
   - key:             readability-identifier-naming.MemberCase
diff --git a/flang/lib/Lower/.clang-tidy b/flang/lib/Lower/.clang-tidy
--- a/flang/lib/Lower/.clang-tidy
+++ b/flang/lib/Lower/.clang-tidy
@@ -1,4 +1,4 @@
-Checks: 'readability-identifier-naming,llvm-include-order,clang-diagnostic-*'
+Checks: '-readability-braces-around-statements,readability-identifier-naming,llvm-include-order,clang-diagnostic-*'
 InheritParentConfig: true
 CheckOptions:
   - key:             readability-identifier-naming.MemberCase
diff --git a/flang/lib/Optimizer/.clang-tidy b/flang/lib/Optimizer/.clang-tidy
--- a/flang/lib/Optimizer/.clang-tidy
+++ b/flang/lib/Optimizer/.clang-tidy
@@ -1,4 +1,4 @@
-Checks: 'readability-identifier-naming,llvm-include-order,clang-diagnostic-*'
+Checks: '-readability-braces-around-statements,readability-identifier-naming,llvm-include-order,clang-diagnostic-*'
 InheritParentConfig: true
 CheckOptions:
   - key:             readability-identifier-naming.MemberCase
diff --git a/flang/lib/Semantics/canonicalize-acc.cpp b/flang/lib/Semantics/canonicalize-acc.cpp
--- a/flang/lib/Semantics/canonicalize-acc.cpp
+++ b/flang/lib/Semantics/canonicalize-acc.cpp
@@ -64,8 +64,9 @@
         std::size_t tileArgNb = listTileExpr.size();
 
         const auto &outer{std::get<std::optional<parser::DoConstruct>>(x.t)};
-        if (outer->IsDoConcurrent())
+        if (outer->IsDoConcurrent()) {
           return; // Tile is not allowed on DO CONURRENT
+        }
         for (const parser::DoConstruct *loop{&*outer}; loop && tileArgNb > 0;
              --tileArgNb) {
           const auto &block{std::get<parser::Block>(loop->t)};
@@ -90,8 +91,9 @@
   template <typename C, typename D>
   void CheckDoConcurrentClauseRestriction(const C &x) {
     const auto &doCons{std::get<std::optional<parser::DoConstruct>>(x.t)};
-    if (!doCons->IsDoConcurrent())
+    if (!doCons->IsDoConcurrent()) {
       return;
+    }
     const auto &beginLoopDirective = std::get<D>(x.t);
     const auto &accClauseList =
         std::get<parser::AccClauseList>(beginLoopDirective.t);
diff --git a/flang/lib/Semantics/check-acc-structure.cpp b/flang/lib/Semantics/check-acc-structure.cpp
--- a/flang/lib/Semantics/check-acc-structure.cpp
+++ b/flang/lib/Semantics/check-acc-structure.cpp
@@ -65,22 +65,25 @@
 }
 
 bool AccStructureChecker::IsInsideComputeConstruct() const {
-  if (dirContext_.size() <= 1)
+  if (dirContext_.size() <= 1) {
     return false;
+  }
 
   // Check all nested context skipping the first one.
   for (std::size_t i = dirContext_.size() - 1; i > 0; --i) {
-    if (IsComputeConstruct(dirContext_[i - 1].directive))
+    if (IsComputeConstruct(dirContext_[i - 1].directive)) {
       return true;
+    }
   }
   return false;
 }
 
 void AccStructureChecker::CheckNotInComputeConstruct() {
-  if (IsInsideComputeConstruct())
+  if (IsInsideComputeConstruct()) {
     context_.Say(GetContext().directiveSource,
         "Directive %s may not be called within a compute region"_err_en_US,
         ContextDirectiveAsFortran());
+  }
 }
 
 void AccStructureChecker::Enter(const parser::AccClause &x) {
@@ -148,7 +151,7 @@
       if (cl != llvm::acc::Clause::ACCC_create &&
           cl != llvm::acc::Clause::ACCC_copyin &&
           cl != llvm::acc::Clause::ACCC_device_resident &&
-          cl != llvm::acc::Clause::ACCC_link)
+          cl != llvm::acc::Clause::ACCC_link) {
         context_.Say(GetContext().directiveSource,
             "%s clause is not allowed on the %s directive in module "
             "declaration "
@@ -156,6 +159,7 @@
             parser::ToUpperCaseLetters(
                 llvm::acc::getOpenACCClauseName(cl).str()),
             ContextDirectiveAsFortran());
+      }
     }
   }
   dirContext_.pop_back();
@@ -368,8 +372,9 @@
   const auto &modifierClause{c.v};
   if (const auto &modifier{
           std::get<std::optional<parser::AccDataModifier>>(modifierClause.t)}) {
-    if (CheckAllowedModifier(llvm::acc::Clause::ACCC_copyin))
+    if (CheckAllowedModifier(llvm::acc::Clause::ACCC_copyin)) {
       return;
+    }
     if (modifier->v != parser::AccDataModifier::Modifier::ReadOnly) {
       context_.Say(GetContext().clauseSource,
           "Only the READONLY modifier is allowed for the %s clause "
@@ -387,8 +392,9 @@
   const auto &modifierClause{c.v};
   if (const auto &modifier{
           std::get<std::optional<parser::AccDataModifier>>(modifierClause.t)}) {
-    if (CheckAllowedModifier(llvm::acc::Clause::ACCC_copyout))
+    if (CheckAllowedModifier(llvm::acc::Clause::ACCC_copyout)) {
       return;
+    }
     if (modifier->v != parser::AccDataModifier::Modifier::Zero) {
       context_.Say(GetContext().clauseSource,
           "Only the ZERO modifier is allowed for the %s clause "
diff --git a/flang/lib/Semantics/check-omp-structure.cpp b/flang/lib/Semantics/check-omp-structure.cpp
--- a/flang/lib/Semantics/check-omp-structure.cpp
+++ b/flang/lib/Semantics/check-omp-structure.cpp
@@ -545,8 +545,9 @@
     // Get collapse level, if given, to find which loops are "associated."
     std::int64_t collapseVal{GetOrdCollapseLevel(x)};
     // Include the top loop if no collapse is specified
-    if (collapseVal == 0)
+    if (collapseVal == 0) {
       collapseVal = 1;
+    }
 
     // Match the loop index variables with the collected symbols from linear
     // clauses.
@@ -560,8 +561,9 @@
             indexVars.erase(*(itrVal.symbol));
           }
           collapseVal--;
-          if (collapseVal == 0)
+          if (collapseVal == 0) {
             break;
+          }
         }
         // Get the next DoConstruct if block is not empty.
         const auto &block{std::get<parser::Block>(loop->t)};
@@ -782,8 +784,9 @@
   const auto &dir{std::get<parser::Verbatim>(x.t)};
   const auto &objectList{std::get<std::optional<parser::OmpObjectList>>(x.t)};
   PushContextAndClauseSets(dir.source, llvm::omp::Directive::OMPD_allocate);
-  if (objectList)
+  if (objectList) {
     CheckIsVarPartOfAnotherVar(dir.source, *objectList);
+  }
 }
 
 void OmpStructureChecker::Leave(const parser::OpenMPExecutableAllocate &x) {
diff --git a/flang/lib/Semantics/resolve-directives.cpp b/flang/lib/Semantics/resolve-directives.cpp
--- a/flang/lib/Semantics/resolve-directives.cpp
+++ b/flang/lib/Semantics/resolve-directives.cpp
@@ -694,20 +694,22 @@
 bool AccAttributeVisitor::Pre(const parser::OpenACCRoutineConstruct &x) {
   const auto &optName{std::get<std::optional<parser::Name>>(x.t)};
   if (optName) {
-    if (!ResolveName(*optName))
+    if (!ResolveName(*optName)) {
       context_.Say((*optName).source,
           "No function or subroutine declared for '%s'"_err_en_US,
           (*optName).source);
+    }
   }
   return true;
 }
 
 bool AccAttributeVisitor::Pre(const parser::AccBindClause &x) {
   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
-    if (!ResolveName(*name))
+    if (!ResolveName(*name)) {
       context_.Say(name->source,
           "No function or subroutine declared for '%s'"_err_en_US,
           name->source);
+    }
   }
   return true;
 }
@@ -750,13 +752,14 @@
     std::visit(
         common::visitors{
             [&](const parser::Designator &designator) {
-              if (!IsLastNameArray(designator))
+              if (!IsLastNameArray(designator)) {
                 context_.Say(designator.source,
                     "Only array element or subarray are allowed in %s directive"_err_en_US,
                     parser::ToUpperCaseLetters(
                         llvm::acc::getOpenACCDirectiveName(
                             GetContext().directive)
                             .str()));
+              }
             },
             [&](const auto &name) {
               context_.Say(name.source,
@@ -777,7 +780,7 @@
         common::visitors{
             [&](const parser::Designator &designator) {
               const auto &name{GetLastName(designator)};
-              if (name.symbol && semantics::IsAssumedSizeArray(*name.symbol))
+              if (name.symbol && semantics::IsAssumedSizeArray(*name.symbol)) {
                 context_.Say(designator.source,
                     "Assumed-size dummy arrays may not appear on the %s "
                     "directive"_err_en_US,
@@ -785,6 +788,7 @@
                         llvm::acc::getOpenACCDirectiveName(
                             GetContext().directive)
                             .str()));
+              }
             },
             [&](const auto &name) {
 
@@ -861,13 +865,14 @@
         common::visitors{
             [&](const parser::Designator &designator) {
               const auto &lastName{GetLastName(designator)};
-              if (!IsAllocatableOrPointer(*lastName.symbol))
+              if (!IsAllocatableOrPointer(*lastName.symbol)) {
                 context_.Say(designator.source,
                     "Argument `%s` on the %s clause must be a variable or "
                     "array with the POINTER or ALLOCATABLE attribute"_err_en_US,
                     lastName.symbol->name(),
                     parser::ToUpperCaseLetters(
                         llvm::acc::getOpenACCClauseName(clause).str()));
+              }
             },
             [&](const auto &name) {
               context_.Say(name.source,
@@ -1349,8 +1354,9 @@
 bool OmpAttributeVisitor::Pre(const parser::OpenMPExecutableAllocate &x) {
   PushContext(x.source, llvm::omp::Directive::OMPD_allocate);
   const auto &list{std::get<std::optional<parser::OmpObjectList>>(x.t)};
-  if (list)
+  if (list) {
     ResolveOmpObjectList(*list, Symbol::Flag::OmpExecutableAllocateDirective);
+  }
   return true;
 }
 
@@ -1376,8 +1382,9 @@
 bool OmpAttributeVisitor::IsNestedInDirective(llvm::omp::Directive directive) {
   if (dirContext_.size() >= 1) {
     for (std::size_t i = dirContext_.size() - 1; i > 0; --i) {
-      if (dirContext_[i - 1].directive == directive)
+      if (dirContext_[i - 1].directive == directive) {
         return true;
+      }
     }
   }
   return false;
@@ -1389,17 +1396,19 @@
   // parser::Unwrap instead of the following loop
   const auto &clauseList{std::get<parser::OmpClauseList>(x.t)};
   for (const auto &clause : clauseList.v) {
-    if (std::get_if<parser::OmpClause::Allocator>(&clause.u))
+    if (std::get_if<parser::OmpClause::Allocator>(&clause.u)) {
       hasAllocator = true;
+    }
   }
 
-  if (IsNestedInDirective(llvm::omp::Directive::OMPD_target) && !hasAllocator)
+  if (IsNestedInDirective(llvm::omp::Directive::OMPD_target) && !hasAllocator) {
     // TODO: expand this check to exclude the case when a requires
     //       directive with the dynamic_allocators clause is present
     //       in the same compilation unit (OMP5.0 2.11.3).
     context_.Say(x.source,
         "ALLOCATE directives that appear in a TARGET region "
         "must specify an allocator clause"_err_en_US);
+  }
   PopContext();
 }
 
@@ -1675,16 +1684,18 @@
 void OmpAttributeVisitor::CheckDataCopyingClause(
     const parser::Name &name, const Symbol &symbol, Symbol::Flag ompFlag) {
   const auto *checkSymbol{&symbol};
-  if (const auto *details{symbol.detailsIf<HostAssocDetails>()})
+  if (const auto *details{symbol.detailsIf<HostAssocDetails>()}) {
     checkSymbol = &details->symbol();
+  }
 
   if (ompFlag == Symbol::Flag::OmpCopyIn) {
     // List of items/objects that can appear in a 'copyin' clause must be
     // 'threadprivate'
-    if (!checkSymbol->test(Symbol::Flag::OmpThreadprivate))
+    if (!checkSymbol->test(Symbol::Flag::OmpThreadprivate)) {
       context_.Say(name.source,
           "Non-THREADPRIVATE object '%s' in COPYIN clause"_err_en_US,
           checkSymbol->name());
+    }
   } else if (ompFlag == Symbol::Flag::OmpCopyPrivate &&
       GetContext().directive == llvm::omp::Directive::OMPD_single) {
     // A list item that appears in a 'copyprivate' clause may not appear on a
@@ -1715,10 +1726,11 @@
     const parser::Name &name, const Symbol &symbol, Symbol::Flag ompFlag) {
   const auto &ultimateSymbol{symbol.GetUltimate()};
   llvm::StringRef clauseName{"PRIVATE"};
-  if (ompFlag == Symbol::Flag::OmpFirstPrivate)
+  if (ompFlag == Symbol::Flag::OmpFirstPrivate) {
     clauseName = "FIRSTPRIVATE";
-  else if (ompFlag == Symbol::Flag::OmpLastPrivate)
+  } else if (ompFlag == Symbol::Flag::OmpLastPrivate) {
     clauseName = "LASTPRIVATE";
+  }
 
   if (ultimateSymbol.test(Symbol::Flag::InNamelist)) {
     context_.Say(name.source,
diff --git a/flang/runtime/ISO_Fortran_binding.cpp b/flang/runtime/ISO_Fortran_binding.cpp
--- a/flang/runtime/ISO_Fortran_binding.cpp
+++ b/flang/runtime/ISO_Fortran_binding.cpp
@@ -236,8 +236,9 @@
   }
   if (type == CFI_type_struct || type == CFI_type_other ||
       IsCharacterType(type)) {
-    if (elem_len <= 0)
+    if (elem_len <= 0) {
       return CFI_INVALID_ELEM_LEN;
+    }
   } else {
     elem_len = MinElemLen(type);
     assert(elem_len > 0 && "Unknown element length for type");
diff --git a/flang/tools/.clang-tidy b/flang/tools/.clang-tidy
new file mode 100644
--- /dev/null
+++ b/flang/tools/.clang-tidy
@@ -0,0 +1,2 @@
+Checks: '-readability-braces-around-statements'
+InheritParentConfig: true
diff --git a/flang/unittests/RuntimeGTest/CrashHandlerFixture.cpp b/flang/unittests/RuntimeGTest/CrashHandlerFixture.cpp
--- a/flang/unittests/RuntimeGTest/CrashHandlerFixture.cpp
+++ b/flang/unittests/RuntimeGTest/CrashHandlerFixture.cpp
@@ -28,7 +28,10 @@
 // Register the crash handler above when creating each unit test in this suite
 void CrashHandlerFixture::SetUp() {
   static bool isCrashHanlderRegistered{false};
-  if (!isCrashHanlderRegistered)
+
+  if (!isCrashHanlderRegistered) {
     Fortran::runtime::Terminator::RegisterCrashHandler(CatchCrash);
+  }
+
   isCrashHanlderRegistered = true;
 }