diff --git a/toolchain/driver/testdata/semantics_builtin_nodes.carbon b/toolchain/driver/testdata/semantics_builtin_nodes.carbon
index ba3dfd4756df..75b13af639b8 100644
--- a/toolchain/driver/testdata/semantics_builtin_nodes.carbon
+++ b/toolchain/driver/testdata/semantics_builtin_nodes.carbon
@@ -18,6 +18,7 @@
 // CHECK:STDOUT: nodes: [
 // CHECK:STDOUT:   {kind: CrossReference, arg0: ir0, arg1: nodeTypeType, type: typeTypeType},
 // CHECK:STDOUT:   {kind: CrossReference, arg0: ir0, arg1: nodeInvalidType, type: typeInvalidType},
+// CHECK:STDOUT:   {kind: CrossReference, arg0: ir0, arg1: nodeBoolType, type: typeTypeType},
 // CHECK:STDOUT:   {kind: CrossReference, arg0: ir0, arg1: nodeIntegerType, type: typeTypeType},
 // CHECK:STDOUT:   {kind: CrossReference, arg0: ir0, arg1: nodeFloatingPointType, type: typeTypeType},
 // CHECK:STDOUT:   {kind: CrossReference, arg0: ir0, arg1: nodeStringType, type: typeTypeType},
diff --git a/toolchain/lexer/token_kind.def b/toolchain/lexer/token_kind.def
index 9ce9970625d1..686de1ef4a57 100644
--- a/toolchain/lexer/token_kind.def
+++ b/toolchain/lexer/token_kind.def
@@ -121,6 +121,7 @@ CARBON_KEYWORD_TOKEN(Api,                 "api")
 CARBON_KEYWORD_TOKEN(As,                  "as")
 CARBON_KEYWORD_TOKEN(Auto,                "auto")
 CARBON_KEYWORD_TOKEN(Base,                "base")
+CARBON_KEYWORD_TOKEN(Bool,                "bool")
 CARBON_KEYWORD_TOKEN(Break,               "break")
 CARBON_KEYWORD_TOKEN(Case,                "case")
 CARBON_KEYWORD_TOKEN(Class,               "class")
diff --git a/toolchain/lowering/lowering_handle.cpp b/toolchain/lowering/lowering_handle.cpp
index 88f4666fc66a..0e692dde2444 100644
--- a/toolchain/lowering/lowering_handle.cpp
+++ b/toolchain/lowering/lowering_handle.cpp
@@ -37,6 +37,30 @@ auto LoweringHandleBindName(LoweringContext& /*context*/,
   // Probably need to do something here, but not necessary for now.
 }
 
+auto LoweringHandleBlockArg(LoweringContext& /*context*/,
+                            SemanticsNodeId /*node_id*/, SemanticsNode node)
+    -> void {
+  CARBON_FATAL() << "TODO: Add support: " << node;
+}
+
+auto LoweringHandleBranch(LoweringContext& /*context*/,
+                          SemanticsNodeId /*node_id*/, SemanticsNode node)
+    -> void {
+  CARBON_FATAL() << "TODO: Add support: " << node;
+}
+
+auto LoweringHandleBranchIf(LoweringContext& /*context*/,
+                            SemanticsNodeId /*node_id*/, SemanticsNode node)
+    -> void {
+  CARBON_FATAL() << "TODO: Add support: " << node;
+}
+
+auto LoweringHandleBranchWithArg(LoweringContext& /*context*/,
+                                 SemanticsNodeId /*node_id*/,
+                                 SemanticsNode node) -> void {
+  CARBON_FATAL() << "TODO: Add support: " << node;
+}
+
 auto LoweringHandleBuiltin(LoweringContext& /*context*/,
                            SemanticsNodeId /*node_id*/, SemanticsNode node)
     -> void {
diff --git a/toolchain/parser/parse_node_kind.def b/toolchain/parser/parse_node_kind.def
index 7d628c53666e..0834e04469a4 100644
--- a/toolchain/parser/parse_node_kind.def
+++ b/toolchain/parser/parse_node_kind.def
@@ -260,15 +260,15 @@ CARBON_PARSE_NODE_KIND_CHILD_COUNT(InfixOperator, 2)
 CARBON_PARSE_NODE_KIND_CHILD_COUNT(PostfixOperator, 1)
 
 // `if` expression + `then` + `else`:
-//   _external_: expression
+//     _external_: expression
+//   IfExpressionIf
+//     _external_: expression
 //   IfExpressionThen
 //   _external_: expression
-//   IfExpressionElse
-//   _external_: expression
-// IfExpression
-CARBON_PARSE_NODE_KIND_CHILD_COUNT(IfExpression, 5)
-CARBON_PARSE_NODE_KIND_CHILD_COUNT(IfExpressionThen, 0)
-CARBON_PARSE_NODE_KIND_CHILD_COUNT(IfExpressionElse, 0)
+// IfExpressionElse
+CARBON_PARSE_NODE_KIND_CHILD_COUNT(IfExpressionIf, 1)
+CARBON_PARSE_NODE_KIND_CHILD_COUNT(IfExpressionThen, 1)
+CARBON_PARSE_NODE_KIND_CHILD_COUNT(IfExpressionElse, 3)
 
 // Struct literals, such as `{.a = 0}`:
 //   StructLiteralOrStructTypeLiteralStart
diff --git a/toolchain/parser/parser_handle_expression.cpp b/toolchain/parser/parser_handle_expression.cpp
index 7bae24ab9deb..e2bba4182303 100644
--- a/toolchain/parser/parser_handle_expression.cpp
+++ b/toolchain/parser/parser_handle_expression.cpp
@@ -28,8 +28,8 @@ auto ParserHandleExpression(ParserContext& context) -> void {
     }
 
     if (context.PositionIs(TokenKind::If)) {
-      context.PushState(ParserState::ExpressionIfFinish);
-      context.PushState(ParserState::ExpressionThen);
+      context.PushState(ParserState::IfExpressionFinish);
+      context.PushState(ParserState::IfExpressionFinishCondition);
     } else {
       context.PushStateForExpressionLoop(ParserState::ExpressionLoopForPrefix,
                                          state.ambient_precedence,
@@ -64,6 +64,7 @@ auto ParserHandleExpressionInPostfix(ParserContext& context) -> void {
     case TokenKind::IntegerLiteral:
     case TokenKind::RealLiteral:
     case TokenKind::StringLiteral:
+    case TokenKind::Bool:
     case TokenKind::IntegerTypeLiteral:
     case TokenKind::UnsignedIntegerTypeLiteral:
     case TokenKind::FloatingPointTypeLiteral:
@@ -209,12 +210,15 @@ auto ParserHandleExpressionLoopForPrefix(ParserContext& context) -> void {
   context.PushState(state);
 }
 
-auto ParserHandleExpressionThen(ParserContext& context) -> void {
+auto ParserHandleIfExpressionFinishCondition(ParserContext& context) -> void {
   auto state = context.PopState();
 
-  if (context.ConsumeAndAddLeafNodeIf(TokenKind::Then,
-                                      ParseNodeKind::IfExpressionThen)) {
-    context.PushState(ParserState::ExpressionElse);
+  context.AddNode(ParseNodeKind::IfExpressionIf, state.token,
+                  state.subtree_start, state.has_error);
+
+  if (context.PositionIs(TokenKind::Then)) {
+    context.PushState(ParserState::IfExpressionFinishThen);
+    context.ConsumeChecked(TokenKind::Then);
     context.PushStateForExpression(*PrecedenceGroup::ForLeading(TokenKind::If));
   } else {
     // TODO: Include the location of the `if` token.
@@ -223,20 +227,24 @@ auto ParserHandleExpressionThen(ParserContext& context) -> void {
     if (!state.has_error) {
       context.emitter().Emit(*context.position(), ExpectedThenAfterIf);
     }
-    // Add placeholders for `then expression else expression`.
-    for (int i = 0; i != 4; ++i) {
-      context.AddLeafNode(ParseNodeKind::InvalidParse, *context.position(),
-                          /*has_error=*/true);
-    }
+    // Add placeholders for `IfExpressionThen` and final `Expression`.
+    context.AddLeafNode(ParseNodeKind::InvalidParse, *context.position(),
+                        /*has_error=*/true);
+    context.AddLeafNode(ParseNodeKind::InvalidParse, *context.position(),
+                        /*has_error=*/true);
     context.ReturnErrorOnState();
   }
 }
 
-auto ParserHandleExpressionElse(ParserContext& context) -> void {
+auto ParserHandleIfExpressionFinishThen(ParserContext& context) -> void {
   auto state = context.PopState();
 
-  if (context.ConsumeAndAddLeafNodeIf(TokenKind::Else,
-                                      ParseNodeKind::IfExpressionElse)) {
+  context.AddNode(ParseNodeKind::IfExpressionThen, state.token,
+                  state.subtree_start, state.has_error);
+
+  if (context.PositionIs(TokenKind::Else)) {
+    context.PushState(ParserState::IfExpressionFinishElse);
+    context.ConsumeChecked(TokenKind::Else);
     context.PushStateForExpression(*PrecedenceGroup::ForLeading(TokenKind::If));
   } else {
     // TODO: Include the location of the `if` token.
@@ -245,20 +253,28 @@ auto ParserHandleExpressionElse(ParserContext& context) -> void {
     if (!state.has_error) {
       context.emitter().Emit(*context.position(), ExpectedElseAfterIf);
     }
-    // Add placeholders for `else expression`.
-    for (int i = 0; i != 2; ++i) {
-      context.AddLeafNode(ParseNodeKind::InvalidParse, *context.position(),
-                          /*has_error=*/true);
-    }
+    // Add placeholder for the final `Expression`.
+    context.AddLeafNode(ParseNodeKind::InvalidParse, *context.position(),
+                        /*has_error=*/true);
     context.ReturnErrorOnState();
   }
 }
 
-auto ParserHandleExpressionIfFinish(ParserContext& context) -> void {
+auto ParserHandleIfExpressionFinishElse(ParserContext& context) -> void {
+  auto else_state = context.PopState();
+
+  // Propagate the location of `else`.
+  auto if_state = context.PopState();
+  if_state.token = else_state.token;
+  if_state.has_error |= else_state.has_error;
+  context.PushState(if_state);
+}
+
+auto ParserHandleIfExpressionFinish(ParserContext& context) -> void {
   auto state = context.PopState();
 
-  context.AddNode(ParseNodeKind::IfExpression, state.token, state.subtree_start,
-                  state.has_error);
+  context.AddNode(ParseNodeKind::IfExpressionElse, state.token,
+                  state.subtree_start, state.has_error);
 }
 
 auto ParserHandleExpressionStatementFinish(ParserContext& context) -> void {
diff --git a/toolchain/parser/parser_state.def b/toolchain/parser/parser_state.def
index b570870ba55a..1ef944ea8c1f 100644
--- a/toolchain/parser/parser_state.def
+++ b/toolchain/parser/parser_state.def
@@ -183,8 +183,8 @@ CARBON_PARSER_STATE_VARIANTS2(Designator, Expression, Struct)
 //
 // If `If`:
 //   1. Expression
-//   2. ExpressionThen
-//   3. ExpressionIfFinish
+//   2. IfExpressionCondition
+//   3. IfExpressionFinish
 // Else if valid prefix operator:
 //   1. Expression
 //   2. ExpressionLoopForPrefix
@@ -246,28 +246,36 @@ CARBON_PARSER_STATE(ExpressionLoopForBinary)
 //   1. ExpressionLoop
 CARBON_PARSER_STATE(ExpressionLoopForPrefix)
 
+// Completes the condition of an `if` expression and handles the `then` token.
+//
+// If `Then`:
+//   1. Expression
+//   2. IfExpressionFinishThen
+// Else:
+//  (state done)
+CARBON_PARSER_STATE(IfExpressionFinishCondition)
+
+// Completes the first alternative in an `if` expression and handles the `else`
+// token.
+//
+// If `Else`:
+//   1. Expression
+//   2. IfExpressionFinishElse
+// Else:
+//  (state done)
+CARBON_PARSER_STATE(IfExpressionFinishThen)
+
+// Completes the second alternative in an `if` expression.
+//
+// Always:
+//  (state done)
+CARBON_PARSER_STATE(IfExpressionFinishElse)
+
 // Completes an IfExpression.
 //
 // Always:
 //   (state done)
-CARBON_PARSER_STATE(ExpressionIfFinish)
-
-// Handles the `then` token in an `if` expression.
-//
-// If `Then`:
-//   1. Expression
-//   2. ExpressionElse
-// Else:
-//  (state done)
-CARBON_PARSER_STATE(ExpressionThen)
-
-// Handles the `else` token in an `if` expression.
-//
-// If `Else`:
-//   1. Expression
-// Else:
-//  (state done)
-CARBON_PARSER_STATE(ExpressionElse)
+CARBON_PARSER_STATE(IfExpressionFinish)
 
 // Handles the `;` for an expression statement, which is different from most
 // keyword statements.
diff --git a/toolchain/parser/testdata/if_expression/basic.carbon b/toolchain/parser/testdata/if_expression/basic.carbon
index aaf62427d6d1..c5056c1ee66c 100644
--- a/toolchain/parser/testdata/if_expression/basic.carbon
+++ b/toolchain/parser/testdata/if_expression/basic.carbon
@@ -8,7 +8,7 @@
 // CHECK:STDOUT:     {kind: 'DeclaredName', text: 'F'},
 // CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:         {kind: 'DeclaredName', text: 'b'},
-// CHECK:STDOUT:         {kind: 'NameReference', text: 'bool'},
+// CHECK:STDOUT:         {kind: 'Literal', text: 'bool'},
 // CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:       {kind: 'ParameterListComma', text: ','},
 // CHECK:STDOUT:         {kind: 'DeclaredName', text: 'x'},
@@ -19,16 +19,16 @@
 // CHECK:STDOUT:         {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 13},
-// CHECK:STDOUT:       {kind: 'NameReference', text: 'bool'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'bool'},
 // CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
 // CHECK:STDOUT:   {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 18},
 // CHECK:STDOUT:     {kind: 'ReturnStatementStart', text: 'return'},
-// CHECK:STDOUT:       {kind: 'NameReference', text: 'b'},
-// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then'},
-// CHECK:STDOUT:       {kind: 'NameReference', text: 'x'},
-// CHECK:STDOUT:       {kind: 'IfExpressionElse', text: 'else'},
+// CHECK:STDOUT:         {kind: 'NameReference', text: 'b'},
+// CHECK:STDOUT:       {kind: 'IfExpressionIf', text: 'if', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'NameReference', text: 'x'},
+// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'NameReference', text: 'y'},
-// CHECK:STDOUT:     {kind: 'IfExpression', text: 'if', subtree_size: 6},
+// CHECK:STDOUT:     {kind: 'IfExpressionElse', text: 'else', subtree_size: 6},
 // CHECK:STDOUT:   {kind: 'ReturnStatement', text: ';', subtree_size: 8},
 // CHECK:STDOUT: {kind: 'FunctionDefinition', text: '}', subtree_size: 27},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
diff --git a/toolchain/parser/testdata/if_expression/fail_condition_missing.carbon b/toolchain/parser/testdata/if_expression/fail_condition_missing.carbon
index c8fc41f10493..7197aad32a35 100644
--- a/toolchain/parser/testdata/if_expression/fail_condition_missing.carbon
+++ b/toolchain/parser/testdata/if_expression/fail_condition_missing.carbon
@@ -14,14 +14,13 @@
 // CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:     {kind: 'VariableInitializer', text: '='},
+// CHECK:STDOUT:         {kind: 'InvalidParse', text: ';', has_error: yes},
+// CHECK:STDOUT:       {kind: 'IfExpressionIf', text: 'if', has_error: yes, subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
 // CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:     {kind: 'IfExpression', text: 'if', has_error: yes, subtree_size: 6},
-// CHECK:STDOUT:   {kind: 'VariableDeclaration', text: ';', subtree_size: 12},
-// CHECK:STDOUT: {kind: 'FunctionDefinition', text: '}', subtree_size: 18},
+// CHECK:STDOUT:     {kind: 'IfExpressionElse', text: 'if', has_error: yes, subtree_size: 5},
+// CHECK:STDOUT:   {kind: 'VariableDeclaration', text: ';', subtree_size: 11},
+// CHECK:STDOUT: {kind: 'FunctionDefinition', text: '}', subtree_size: 17},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT: ]
 
diff --git a/toolchain/parser/testdata/if_expression/fail_else_expr_missing.carbon b/toolchain/parser/testdata/if_expression/fail_else_expr_missing.carbon
index 021332457980..0b817742042d 100644
--- a/toolchain/parser/testdata/if_expression/fail_else_expr_missing.carbon
+++ b/toolchain/parser/testdata/if_expression/fail_else_expr_missing.carbon
@@ -14,12 +14,12 @@
 // CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:     {kind: 'VariableInitializer', text: '='},
-// CHECK:STDOUT:       {kind: 'NameReference', text: 'true'},
-// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then'},
-// CHECK:STDOUT:       {kind: 'Literal', text: '1'},
-// CHECK:STDOUT:       {kind: 'IfExpressionElse', text: 'else'},
+// CHECK:STDOUT:         {kind: 'NameReference', text: 'true'},
+// CHECK:STDOUT:       {kind: 'IfExpressionIf', text: 'if', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'Literal', text: '1'},
+// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:     {kind: 'IfExpression', text: 'if', has_error: yes, subtree_size: 6},
+// CHECK:STDOUT:     {kind: 'IfExpressionElse', text: 'else', has_error: yes, subtree_size: 6},
 // CHECK:STDOUT:   {kind: 'VariableDeclaration', text: ';', subtree_size: 12},
 // CHECK:STDOUT: {kind: 'FunctionDefinition', text: '}', subtree_size: 18},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
diff --git a/toolchain/parser/testdata/if_expression/fail_else_missing.carbon b/toolchain/parser/testdata/if_expression/fail_else_missing.carbon
index 23fcaa30a067..336663d19ed5 100644
--- a/toolchain/parser/testdata/if_expression/fail_else_missing.carbon
+++ b/toolchain/parser/testdata/if_expression/fail_else_missing.carbon
@@ -14,12 +14,12 @@
 // CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:     {kind: 'VariableInitializer', text: '='},
-// CHECK:STDOUT:       {kind: 'NameReference', text: 'true'},
-// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then'},
-// CHECK:STDOUT:       {kind: 'Literal', text: '1'},
+// CHECK:STDOUT:         {kind: 'NameReference', text: 'true'},
+// CHECK:STDOUT:       {kind: 'IfExpressionIf', text: 'if', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'Literal', text: '1'},
+// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:     {kind: 'IfExpression', text: 'if', has_error: yes, subtree_size: 6},
+// CHECK:STDOUT:     {kind: 'IfExpressionElse', text: 'if', has_error: yes, subtree_size: 6},
 // CHECK:STDOUT:   {kind: 'VariableDeclaration', text: ';', subtree_size: 12},
 // CHECK:STDOUT: {kind: 'FunctionDefinition', text: '}', subtree_size: 18},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
diff --git a/toolchain/parser/testdata/if_expression/fail_then_expr_missing.carbon b/toolchain/parser/testdata/if_expression/fail_then_expr_missing.carbon
index 3c78e4d1e3e5..ec136930c384 100644
--- a/toolchain/parser/testdata/if_expression/fail_then_expr_missing.carbon
+++ b/toolchain/parser/testdata/if_expression/fail_then_expr_missing.carbon
@@ -14,12 +14,12 @@
 // CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:     {kind: 'VariableInitializer', text: '='},
-// CHECK:STDOUT:       {kind: 'NameReference', text: 'true'},
-// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then'},
+// CHECK:STDOUT:         {kind: 'NameReference', text: 'true'},
+// CHECK:STDOUT:       {kind: 'IfExpressionIf', text: 'if', subtree_size: 2},
+// CHECK:STDOUT:         {kind: 'InvalidParse', text: ';', has_error: yes},
+// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then', has_error: yes, subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:     {kind: 'IfExpression', text: 'if', has_error: yes, subtree_size: 6},
+// CHECK:STDOUT:     {kind: 'IfExpressionElse', text: 'if', has_error: yes, subtree_size: 6},
 // CHECK:STDOUT:   {kind: 'VariableDeclaration', text: ';', subtree_size: 12},
 // CHECK:STDOUT: {kind: 'FunctionDefinition', text: '}', subtree_size: 18},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
diff --git a/toolchain/parser/testdata/if_expression/fail_then_missing.carbon b/toolchain/parser/testdata/if_expression/fail_then_missing.carbon
index e6ad066d67b6..e26ef9042753 100644
--- a/toolchain/parser/testdata/if_expression/fail_then_missing.carbon
+++ b/toolchain/parser/testdata/if_expression/fail_then_missing.carbon
@@ -14,14 +14,13 @@
 // CHECK:STDOUT:       {kind: 'Literal', text: 'i32'},
 // CHECK:STDOUT:     {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:     {kind: 'VariableInitializer', text: '='},
-// CHECK:STDOUT:       {kind: 'NameReference', text: 'true'},
+// CHECK:STDOUT:         {kind: 'NameReference', text: 'true'},
+// CHECK:STDOUT:       {kind: 'IfExpressionIf', text: 'if', subtree_size: 2},
 // CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
 // CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:       {kind: 'InvalidParse', text: ';', has_error: yes},
-// CHECK:STDOUT:     {kind: 'IfExpression', text: 'if', has_error: yes, subtree_size: 6},
-// CHECK:STDOUT:   {kind: 'VariableDeclaration', text: ';', subtree_size: 12},
-// CHECK:STDOUT: {kind: 'FunctionDefinition', text: '}', subtree_size: 18},
+// CHECK:STDOUT:     {kind: 'IfExpressionElse', text: 'if', has_error: yes, subtree_size: 5},
+// CHECK:STDOUT:   {kind: 'VariableDeclaration', text: ';', subtree_size: 11},
+// CHECK:STDOUT: {kind: 'FunctionDefinition', text: '}', subtree_size: 17},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
 // CHECK:STDOUT: ]
 
diff --git a/toolchain/parser/testdata/if_expression/precedence.carbon b/toolchain/parser/testdata/if_expression/precedence.carbon
index d2c5dc990794..e69ff6eceb51 100644
--- a/toolchain/parser/testdata/if_expression/precedence.carbon
+++ b/toolchain/parser/testdata/if_expression/precedence.carbon
@@ -8,25 +8,25 @@
 // CHECK:STDOUT:     {kind: 'DeclaredName', text: 'F'},
 // CHECK:STDOUT:       {kind: 'ParameterListStart', text: '('},
 // CHECK:STDOUT:         {kind: 'DeclaredName', text: 'b'},
-// CHECK:STDOUT:         {kind: 'NameReference', text: 'bool'},
+// CHECK:STDOUT:         {kind: 'Literal', text: 'bool'},
 // CHECK:STDOUT:       {kind: 'PatternBinding', text: ':', subtree_size: 3},
 // CHECK:STDOUT:     {kind: 'ParameterList', text: ')', subtree_size: 5},
-// CHECK:STDOUT:       {kind: 'NameReference', text: 'bool'},
+// CHECK:STDOUT:       {kind: 'Literal', text: 'bool'},
 // CHECK:STDOUT:     {kind: 'ReturnType', text: '->', subtree_size: 2},
 // CHECK:STDOUT:   {kind: 'FunctionDefinitionStart', text: '{', subtree_size: 10},
 // CHECK:STDOUT:     {kind: 'ReturnStatementStart', text: 'return'},
-// CHECK:STDOUT:         {kind: 'NameReference', text: 'b'},
-// CHECK:STDOUT:         {kind: 'NameReference', text: 'b'},
-// CHECK:STDOUT:       {kind: 'InfixOperator', text: 'and', subtree_size: 3},
-// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then'},
-// CHECK:STDOUT:         {kind: 'NameReference', text: 'b'},
-// CHECK:STDOUT:         {kind: 'NameReference', text: 'b'},
-// CHECK:STDOUT:       {kind: 'InfixOperator', text: 'and', subtree_size: 3},
-// CHECK:STDOUT:       {kind: 'IfExpressionElse', text: 'else'},
+// CHECK:STDOUT:           {kind: 'NameReference', text: 'b'},
+// CHECK:STDOUT:           {kind: 'NameReference', text: 'b'},
+// CHECK:STDOUT:         {kind: 'InfixOperator', text: 'and', subtree_size: 3},
+// CHECK:STDOUT:       {kind: 'IfExpressionIf', text: 'if', subtree_size: 4},
+// CHECK:STDOUT:           {kind: 'NameReference', text: 'b'},
+// CHECK:STDOUT:           {kind: 'NameReference', text: 'b'},
+// CHECK:STDOUT:         {kind: 'InfixOperator', text: 'and', subtree_size: 3},
+// CHECK:STDOUT:       {kind: 'IfExpressionThen', text: 'then', subtree_size: 4},
 // CHECK:STDOUT:         {kind: 'NameReference', text: 'b'},
 // CHECK:STDOUT:         {kind: 'NameReference', text: 'b'},
 // CHECK:STDOUT:       {kind: 'InfixOperator', text: 'or', subtree_size: 3},
-// CHECK:STDOUT:     {kind: 'IfExpression', text: 'if', subtree_size: 12},
+// CHECK:STDOUT:     {kind: 'IfExpressionElse', text: 'else', subtree_size: 12},
 // CHECK:STDOUT:   {kind: 'ReturnStatement', text: ';', subtree_size: 14},
 // CHECK:STDOUT: {kind: 'FunctionDefinition', text: '}', subtree_size: 25},
 // CHECK:STDOUT: {kind: 'FileEnd', text: ''},
diff --git a/toolchain/semantics/semantics_builtin_kind.def b/toolchain/semantics/semantics_builtin_kind.def
index c283024fa6bb..f54cbe9d6a32 100644
--- a/toolchain/semantics/semantics_builtin_kind.def
+++ b/toolchain/semantics/semantics_builtin_kind.def
@@ -50,6 +50,9 @@ CARBON_SEMANTICS_BUILTIN_KIND(InvalidType, "<unknown>")
 // Keeping distinct placeholders can help find usages for later fixes.
 // -----------------------------------------------------------------------------
 
+// The type of bool literals and branch conditions, bool.
+CARBON_SEMANTICS_BUILTIN_KIND(BoolType, "bool")
+
 // The type of integer values and integer literals, currently always i32.
 CARBON_SEMANTICS_BUILTIN_KIND(IntegerType, "i32")
 
diff --git a/toolchain/semantics/semantics_context.cpp b/toolchain/semantics/semantics_context.cpp
index 412b4340991c..dd240e7144c3 100644
--- a/toolchain/semantics/semantics_context.cpp
+++ b/toolchain/semantics/semantics_context.cpp
@@ -61,7 +61,11 @@ auto SemanticsContext::VerifyOnFinish() -> void {
 }
 
 auto SemanticsContext::AddNode(SemanticsNode node) -> SemanticsNodeId {
-  auto block = node_block_stack_.PeekForAdd();
+  return AddNodeToBlock(node_block_stack_.PeekForAdd(), node);
+}
+
+auto SemanticsContext::AddNodeToBlock(SemanticsNodeBlockId block,
+                                      SemanticsNode node) -> SemanticsNodeId {
   CARBON_VLOG() << "AddNode " << block << ": " << node << "\n";
   return semantics_ir_->AddNode(block, node);
 }
diff --git a/toolchain/semantics/semantics_context.h b/toolchain/semantics/semantics_context.h
index ad0b373673e9..d44cc4efbb87 100644
--- a/toolchain/semantics/semantics_context.h
+++ b/toolchain/semantics/semantics_context.h
@@ -35,6 +35,10 @@ class SemanticsContext {
   // Adds a node to the current block, returning the produced ID.
   auto AddNode(SemanticsNode node) -> SemanticsNodeId;
 
+  // Adds a node to the given block, returning the produced ID.
+  auto AddNodeToBlock(SemanticsNodeBlockId block, SemanticsNode node)
+      -> SemanticsNodeId;
+
   // Pushes a parse tree node onto the stack, storing the SemanticsNode as the
   // result.
   auto AddNodeAndPush(ParseTree::Node parse_node, SemanticsNode node) -> void;
diff --git a/toolchain/semantics/semantics_handle.cpp b/toolchain/semantics/semantics_handle.cpp
index 7c89cbb2d6f4..eafc8cfa6697 100644
--- a/toolchain/semantics/semantics_handle.cpp
+++ b/toolchain/semantics/semantics_handle.cpp
@@ -178,21 +178,6 @@ auto SemanticsHandleIfConditionStart(SemanticsContext& context,
   return context.TODO(parse_node, "HandleIfConditionStart");
 }
 
-auto SemanticsHandleIfExpression(SemanticsContext& context,
-                                 ParseTree::Node parse_node) -> bool {
-  return context.TODO(parse_node, "HandleIfExpression");
-}
-
-auto SemanticsHandleIfExpressionElse(SemanticsContext& context,
-                                     ParseTree::Node parse_node) -> bool {
-  return context.TODO(parse_node, "HandleIfExpressionElse");
-}
-
-auto SemanticsHandleIfExpressionThen(SemanticsContext& context,
-                                     ParseTree::Node parse_node) -> bool {
-  return context.TODO(parse_node, "HandleIfExpressionThen");
-}
-
 auto SemanticsHandleIfStatement(SemanticsContext& context,
                                 ParseTree::Node parse_node) -> bool {
   return context.TODO(parse_node, "HandleIfStatement");
@@ -275,6 +260,10 @@ auto SemanticsHandleLiteral(SemanticsContext& context,
               id));
       break;
     }
+    case TokenKind::Bool: {
+      context.node_stack().Push(parse_node, SemanticsNodeId::BuiltinBoolType);
+      break;
+    }
     case TokenKind::IntegerTypeLiteral: {
       auto text = context.tokens().GetTokenText(token);
       if (text != "i32") {
diff --git a/toolchain/semantics/semantics_handle_function.cpp b/toolchain/semantics/semantics_handle_function.cpp
index 9fe0de7bcece..029429dfc9a9 100644
--- a/toolchain/semantics/semantics_handle_function.cpp
+++ b/toolchain/semantics/semantics_handle_function.cpp
@@ -18,17 +18,10 @@ auto SemanticsHandleFunctionDefinition(SemanticsContext& context,
          ParseNodeKind::FunctionDefinitionStart) {
     context.node_stack().PopAndIgnore();
   }
-  auto function_id = context.node_stack().Pop<SemanticsFunctionId>(
-      ParseNodeKind::FunctionDefinitionStart);
-
+  context.node_stack().PopAndDiscardId(ParseNodeKind::FunctionDefinitionStart);
   context.return_scope_stack().pop_back();
   context.PopScope();
-  auto body_id = context.node_block_stack().Pop();
-  auto& function = context.semantics_ir().GetFunction(function_id);
-  CARBON_CHECK(!function.body_id.is_valid())
-      << "Already have function body: " << function.body_id;
-  function.body_id = body_id;
-
+  context.node_block_stack().Pop();
   return true;
 }
 
@@ -54,18 +47,21 @@ auto SemanticsHandleFunctionDefinitionStart(SemanticsContext& context,
   auto name_str = context.parse_tree().GetNodeText(name_node);
   auto name_id = context.semantics_ir().AddString(name_str);
 
-  // Add the callable, but with an invalid body for now. The body ID is only
-  // finalized on function completion.
+  // Create the entry block.
+  auto outer_block = context.node_block_stack().PeekForAdd();
+  context.node_block_stack().Push();
+
+  // Add the callable.
   auto function_id = context.semantics_ir().AddFunction(
       {.name_id = name_id,
        .param_refs_id = param_refs_id,
        .return_type_id = return_type_id,
-       .body_id = SemanticsNodeBlockId::Invalid});
-  auto decl_id = context.AddNode(
+       .body_id = context.node_block_stack().PeekForAdd()});
+  auto decl_id = context.AddNodeToBlock(
+      outer_block,
       SemanticsNode::FunctionDeclaration::Make(fn_node, function_id));
   context.AddNameToLookup(name_node, name_id, decl_id);
 
-  context.node_block_stack().Push();
   context.PushScope();
   for (auto ref_id : context.semantics_ir().GetNodeBlock(param_refs_id)) {
     auto ref = context.semantics_ir().GetNode(ref_id);
diff --git a/toolchain/semantics/semantics_handle_if_expression.cpp b/toolchain/semantics/semantics_handle_if_expression.cpp
new file mode 100644
index 000000000000..5294670c9aef
--- /dev/null
+++ b/toolchain/semantics/semantics_handle_if_expression.cpp
@@ -0,0 +1,77 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include "toolchain/semantics/semantics_context.h"
+
+namespace Carbon {
+
+auto SemanticsHandleIfExpressionIf(SemanticsContext& context,
+                                   ParseTree::Node if_node) -> bool {
+  auto cond_value_id = context.node_stack().Pop<SemanticsNodeId>();
+
+  context.node_stack().Push(if_node);
+
+  // Convert the condition to `bool`.
+  cond_value_id = context.ImplicitAsRequired(
+      if_node, cond_value_id,
+      context.CanonicalizeType(SemanticsNodeId::BuiltinBoolType));
+
+  // Stop emitting the current block. We'll add some branch instructions to it
+  // later, but we don't want it on the stack any more.
+  auto if_block_id = context.node_block_stack().PeekForAdd();
+  context.node_block_stack().Pop();
+
+  // Create the resumption block, `else` block, and `then` block, and branches
+  // to them.
+  context.node_block_stack().Push();
+  auto else_block_id = context.node_block_stack().PushForAdd();
+  auto then_block_id = context.node_block_stack().PushForAdd();
+  context.AddNodeToBlock(
+      if_block_id,
+      SemanticsNode::BranchIf::Make(if_node, then_block_id, cond_value_id));
+  context.AddNodeToBlock(if_block_id,
+                         SemanticsNode::Branch::Make(if_node, else_block_id));
+  return true;
+}
+
+auto SemanticsHandleIfExpressionThen(SemanticsContext& context,
+                                     ParseTree::Node then_node) -> bool {
+  context.node_stack().Push(then_node, context.node_block_stack().Pop());
+  return true;
+}
+
+auto SemanticsHandleIfExpressionElse(SemanticsContext& context,
+                                     ParseTree::Node else_node) -> bool {
+  auto else_value_id = context.node_stack().Pop<SemanticsNodeId>();
+  auto [then_node, then_end_block_id] =
+      context.node_stack().PopWithParseNode<SemanticsNodeBlockId>(
+          ParseNodeKind::IfExpressionThen);
+  auto then_value_id = context.node_stack().Pop<SemanticsNodeId>();
+  auto if_node =
+      context.node_stack().PopForSoloParseNode(ParseNodeKind::IfExpressionIf);
+
+  // Convert the `else` value to the `then` value's type, and finish the `else`
+  // block.
+  // TODO: Find a common type, and convert both operands to it instead.
+  auto result_type_id = context.semantics_ir().GetNode(then_value_id).type_id();
+  else_value_id =
+      context.ImplicitAsRequired(else_node, else_value_id, result_type_id);
+  auto else_end_block_id = context.node_block_stack().Pop();
+
+  // Create branches to the resumption block.
+  auto resume_block_id = context.node_block_stack().PeekForAdd();
+  context.AddNodeToBlock(then_end_block_id,
+                         SemanticsNode::BranchWithArg::Make(
+                             then_node, resume_block_id, then_value_id));
+  context.AddNodeToBlock(else_end_block_id,
+                         SemanticsNode::BranchWithArg::Make(
+                             else_node, resume_block_id, else_value_id));
+
+  // Obtain the value in the resumption block and push it.
+  context.AddNodeAndPush(
+      if_node, SemanticsNode::BlockArg::Make(if_node, result_type_id));
+  return true;
+}
+
+}  // namespace Carbon
diff --git a/toolchain/semantics/semantics_ir.cpp b/toolchain/semantics/semantics_ir.cpp
index 6df1cc559920..2d2a33d0d181 100644
--- a/toolchain/semantics/semantics_ir.cpp
+++ b/toolchain/semantics/semantics_ir.cpp
@@ -198,6 +198,10 @@ auto SemanticsIR::StringifyType(SemanticsTypeId type_id) -> std::string {
       case SemanticsNodeKind::Assign:
       case SemanticsNodeKind::BinaryOperatorAdd:
       case SemanticsNodeKind::BindName:
+      case SemanticsNodeKind::BlockArg:
+      case SemanticsNodeKind::Branch:
+      case SemanticsNodeKind::BranchIf:
+      case SemanticsNodeKind::BranchWithArg:
       case SemanticsNodeKind::Builtin:
       case SemanticsNodeKind::Call:
       case SemanticsNodeKind::CodeBlock:
diff --git a/toolchain/semantics/semantics_node.h b/toolchain/semantics/semantics_node.h
index 6b05de13470e..521ac631040c 100644
--- a/toolchain/semantics/semantics_node.h
+++ b/toolchain/semantics/semantics_node.h
@@ -262,6 +262,19 @@ class SemanticsNode {
                                           SemanticsStringId /*name_id*/,
                                           SemanticsNodeId /*node_id*/>;
 
+  using BlockArg = Factory<SemanticsNodeKind::BlockArg>;
+
+  using Branch = FactoryNoType<SemanticsNodeKind::Branch,
+                               SemanticsNodeBlockId /*target_id*/>;
+
+  using BranchIf = FactoryNoType<SemanticsNodeKind::BranchIf,
+                                 SemanticsNodeBlockId /*target_id*/,
+                                 SemanticsNodeId /*cond_id*/>;
+
+  using BranchWithArg = FactoryNoType<SemanticsNodeKind::BranchWithArg,
+                                      SemanticsNodeBlockId /*target_id*/,
+                                      SemanticsNodeId /*arg*/>;
+
   class Builtin {
    public:
     static auto Make(SemanticsBuiltinKind builtin_kind, SemanticsTypeId type_id)
diff --git a/toolchain/semantics/semantics_node_block_stack.h b/toolchain/semantics/semantics_node_block_stack.h
index 7a724b0cebf8..3d850bca0c83 100644
--- a/toolchain/semantics/semantics_node_block_stack.h
+++ b/toolchain/semantics/semantics_node_block_stack.h
@@ -27,6 +27,12 @@ class SemanticsNodeBlockStack {
   // order to support lazy allocation.
   auto Push() -> void;
 
+  // Allocates and pushes a new node block.
+  auto PushForAdd() -> SemanticsNodeBlockId {
+    Push();
+    return PeekForAdd();
+  }
+
   // Peeks at the top node block. This does not trigger lazy allocation, so the
   // returned node block may be invalid.
   auto Peek() -> SemanticsNodeBlockId { return stack_.back(); }
diff --git a/toolchain/semantics/semantics_node_kind.def b/toolchain/semantics/semantics_node_kind.def
index 784e222a9ae1..b70903dbfd23 100644
--- a/toolchain/semantics/semantics_node_kind.def
+++ b/toolchain/semantics/semantics_node_kind.def
@@ -23,6 +23,10 @@ CARBON_SEMANTICS_NODE_KIND(CrossReference)
 CARBON_SEMANTICS_NODE_KIND(Assign)
 CARBON_SEMANTICS_NODE_KIND(BinaryOperatorAdd)
 CARBON_SEMANTICS_NODE_KIND(BindName)
+CARBON_SEMANTICS_NODE_KIND(BlockArg)
+CARBON_SEMANTICS_NODE_KIND(Branch)
+CARBON_SEMANTICS_NODE_KIND(BranchIf)
+CARBON_SEMANTICS_NODE_KIND(BranchWithArg)
 CARBON_SEMANTICS_NODE_KIND(Builtin)
 CARBON_SEMANTICS_NODE_KIND(Call)
 CARBON_SEMANTICS_NODE_KIND(CodeBlock)
diff --git a/toolchain/semantics/testdata/basics/fail_name_lookup.carbon b/toolchain/semantics/testdata/basics/fail_name_lookup.carbon
index 9fed8695edf8..439b679f61fa 100644
--- a/toolchain/semantics/testdata/basics/fail_name_lookup.carbon
+++ b/toolchain/semantics/testdata/basics/fail_name_lookup.carbon
@@ -5,7 +5,7 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block0},
+// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block2},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -26,6 +26,8 @@
 // CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+0,
 // CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
 
 fn Main() {
diff --git a/toolchain/semantics/testdata/function/call/fail_param_count.carbon b/toolchain/semantics/testdata/function/call/fail_param_count.carbon
index 1b4162a4885f..c9641dea66ab 100644
--- a/toolchain/semantics/testdata/function/call/fail_param_count.carbon
+++ b/toolchain/semantics/testdata/function/call/fail_param_count.carbon
@@ -5,10 +5,10 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block0},
-// CHECK:STDOUT:   {name: str2, param_refs: block3, body: block0},
-// CHECK:STDOUT:   {name: str4, param_refs: block5, body: block0},
-// CHECK:STDOUT:   {name: str5, param_refs: block0, body: block6},
+// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block2},
+// CHECK:STDOUT:   {name: str2, param_refs: block4, body: block5},
+// CHECK:STDOUT:   {name: str4, param_refs: block7, body: block8},
+// CHECK:STDOUT:   {name: str5, param_refs: block0, body: block9},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT:   1,
@@ -66,6 +66,8 @@
 // CHECK:STDOUT:     node+9,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+1,
 // CHECK:STDOUT:     node+2,
 // CHECK:STDOUT:   ],
@@ -73,6 +75,8 @@
 // CHECK:STDOUT:     node+2,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+4,
 // CHECK:STDOUT:     node+5,
 // CHECK:STDOUT:     node+6,
@@ -83,6 +87,8 @@
 // CHECK:STDOUT:     node+7,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+10,
 // CHECK:STDOUT:     node+11,
 // CHECK:STDOUT:     node+12,
diff --git a/toolchain/semantics/testdata/function/call/fail_param_type.carbon b/toolchain/semantics/testdata/function/call/fail_param_type.carbon
index e83edf36a404..05f87b55c615 100644
--- a/toolchain/semantics/testdata/function/call/fail_param_type.carbon
+++ b/toolchain/semantics/testdata/function/call/fail_param_type.carbon
@@ -5,8 +5,8 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block0},
-// CHECK:STDOUT:   {name: str2, param_refs: block0, body: block4},
+// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block4},
+// CHECK:STDOUT:   {name: str2, param_refs: block0, body: block5},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -46,6 +46,8 @@
 // CHECK:STDOUT:     node+3,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+4,
 // CHECK:STDOUT:     node+5,
 // CHECK:STDOUT:   ],
diff --git a/toolchain/semantics/testdata/function/call/more_param_ir.carbon b/toolchain/semantics/testdata/function/call/more_param_ir.carbon
index 5a2dfdcb2ff5..4225e5de0583 100644
--- a/toolchain/semantics/testdata/function/call/more_param_ir.carbon
+++ b/toolchain/semantics/testdata/function/call/more_param_ir.carbon
@@ -5,8 +5,8 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str3, param_refs: block2, body: block0},
-// CHECK:STDOUT:   {name: str4, param_refs: block0, body: block4},
+// CHECK:STDOUT:   {name: str3, param_refs: block2, body: block4},
+// CHECK:STDOUT:   {name: str4, param_refs: block0, body: block5},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT:   1,
@@ -50,7 +50,7 @@
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+16, type: type0},
 // CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int5, type: type0},
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+18, type: type0},
-// CHECK:STDOUT:   {kind: Call, arg0: block5, arg1: function0},
+// CHECK:STDOUT:   {kind: Call, arg0: block6, arg1: function0},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: node_blocks: [
 // CHECK:STDOUT:   [
@@ -73,6 +73,8 @@
 // CHECK:STDOUT:     node+7,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+8,
 // CHECK:STDOUT:     node+9,
 // CHECK:STDOUT:     node+10,
diff --git a/toolchain/semantics/testdata/function/call/params_one.carbon b/toolchain/semantics/testdata/function/call/params_one.carbon
index f4f8e5b1e184..3094c285aed4 100644
--- a/toolchain/semantics/testdata/function/call/params_one.carbon
+++ b/toolchain/semantics/testdata/function/call/params_one.carbon
@@ -5,8 +5,8 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block0},
-// CHECK:STDOUT:   {name: str2, param_refs: block0, body: block4},
+// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block4},
+// CHECK:STDOUT:   {name: str2, param_refs: block0, body: block5},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT:   1,
@@ -29,7 +29,7 @@
 // CHECK:STDOUT:   {kind: FunctionDeclaration, arg0: function1},
 // CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int0, type: type0},
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+4, type: type0},
-// CHECK:STDOUT:   {kind: Call, arg0: block5, arg1: function0},
+// CHECK:STDOUT:   {kind: Call, arg0: block6, arg1: function0},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: node_blocks: [
 // CHECK:STDOUT:   [
@@ -46,6 +46,8 @@
 // CHECK:STDOUT:     node+3,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+4,
 // CHECK:STDOUT:     node+5,
 // CHECK:STDOUT:     node+6,
diff --git a/toolchain/semantics/testdata/function/call/params_one_comma.carbon b/toolchain/semantics/testdata/function/call/params_one_comma.carbon
index 5ac3e2f7e1df..c3923fbcc37b 100644
--- a/toolchain/semantics/testdata/function/call/params_one_comma.carbon
+++ b/toolchain/semantics/testdata/function/call/params_one_comma.carbon
@@ -5,8 +5,8 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block0},
-// CHECK:STDOUT:   {name: str2, param_refs: block0, body: block4},
+// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block4},
+// CHECK:STDOUT:   {name: str2, param_refs: block0, body: block5},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT:   1,
@@ -30,10 +30,10 @@
 // CHECK:STDOUT:   {kind: FunctionDeclaration, arg0: function1},
 // CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int0, type: type0},
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+4, type: type0},
-// CHECK:STDOUT:   {kind: Call, arg0: block5, arg1: function0},
+// CHECK:STDOUT:   {kind: Call, arg0: block6, arg1: function0},
 // CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int1, type: type0},
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+7, type: type0},
-// CHECK:STDOUT:   {kind: Call, arg0: block6, arg1: function0},
+// CHECK:STDOUT:   {kind: Call, arg0: block7, arg1: function0},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: node_blocks: [
 // CHECK:STDOUT:   [
@@ -50,6 +50,8 @@
 // CHECK:STDOUT:     node+3,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+4,
 // CHECK:STDOUT:     node+5,
 // CHECK:STDOUT:     node+6,
diff --git a/toolchain/semantics/testdata/function/call/params_two.carbon b/toolchain/semantics/testdata/function/call/params_two.carbon
index 41beda7f60e1..333fba654a52 100644
--- a/toolchain/semantics/testdata/function/call/params_two.carbon
+++ b/toolchain/semantics/testdata/function/call/params_two.carbon
@@ -5,8 +5,8 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str2, param_refs: block2, body: block0},
-// CHECK:STDOUT:   {name: str3, param_refs: block0, body: block4},
+// CHECK:STDOUT:   {name: str2, param_refs: block2, body: block4},
+// CHECK:STDOUT:   {name: str3, param_refs: block0, body: block5},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT:   1,
@@ -35,7 +35,7 @@
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+6, type: type0},
 // CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int1, type: type0},
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+8, type: type0},
-// CHECK:STDOUT:   {kind: Call, arg0: block5, arg1: function0},
+// CHECK:STDOUT:   {kind: Call, arg0: block6, arg1: function0},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: node_blocks: [
 // CHECK:STDOUT:   [
@@ -55,6 +55,8 @@
 // CHECK:STDOUT:     node+5,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+6,
 // CHECK:STDOUT:     node+7,
 // CHECK:STDOUT:     node+8,
diff --git a/toolchain/semantics/testdata/function/call/params_two_comma.carbon b/toolchain/semantics/testdata/function/call/params_two_comma.carbon
index 50afe4998794..f65b74d5ad74 100644
--- a/toolchain/semantics/testdata/function/call/params_two_comma.carbon
+++ b/toolchain/semantics/testdata/function/call/params_two_comma.carbon
@@ -5,8 +5,8 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str2, param_refs: block2, body: block0},
-// CHECK:STDOUT:   {name: str3, param_refs: block0, body: block4},
+// CHECK:STDOUT:   {name: str2, param_refs: block2, body: block4},
+// CHECK:STDOUT:   {name: str3, param_refs: block0, body: block5},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT:   1,
@@ -37,12 +37,12 @@
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+6, type: type0},
 // CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int1, type: type0},
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+8, type: type0},
-// CHECK:STDOUT:   {kind: Call, arg0: block5, arg1: function0},
+// CHECK:STDOUT:   {kind: Call, arg0: block6, arg1: function0},
 // CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int2, type: type0},
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+11, type: type0},
 // CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int3, type: type0},
 // CHECK:STDOUT:   {kind: StubReference, arg0: node+13, type: type0},
-// CHECK:STDOUT:   {kind: Call, arg0: block6, arg1: function0},
+// CHECK:STDOUT:   {kind: Call, arg0: block7, arg1: function0},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: node_blocks: [
 // CHECK:STDOUT:   [
@@ -62,6 +62,8 @@
 // CHECK:STDOUT:     node+5,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+6,
 // CHECK:STDOUT:     node+7,
 // CHECK:STDOUT:     node+8,
diff --git a/toolchain/semantics/testdata/function/call/params_zero.carbon b/toolchain/semantics/testdata/function/call/params_zero.carbon
index 50ea6007bbc4..111e132ebaa5 100644
--- a/toolchain/semantics/testdata/function/call/params_zero.carbon
+++ b/toolchain/semantics/testdata/function/call/params_zero.carbon
@@ -5,8 +5,8 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block0},
-// CHECK:STDOUT:   {name: str1, param_refs: block0, body: block2},
+// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block2},
+// CHECK:STDOUT:   {name: str1, param_refs: block0, body: block3},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -32,6 +32,8 @@
 // CHECK:STDOUT:     node+1,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+2,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
diff --git a/toolchain/semantics/testdata/function/definition/fail_param_name_conflict.carbon b/toolchain/semantics/testdata/function/definition/fail_param_name_conflict.carbon
index 1594468c8510..b09f4457a9bb 100644
--- a/toolchain/semantics/testdata/function/definition/fail_param_name_conflict.carbon
+++ b/toolchain/semantics/testdata/function/definition/fail_param_name_conflict.carbon
@@ -5,7 +5,7 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block0},
+// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block4},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -42,6 +42,8 @@
 // CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+4,
 // CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
 
 // CHECK:STDERR: fail_param_name_conflict.carbon:[[@LINE+2]]:16: Redefining a in the same scope.
diff --git a/toolchain/semantics/testdata/function/definition/order.carbon b/toolchain/semantics/testdata/function/definition/order.carbon
index 517e6e4b4084..6b25ef48edd3 100644
--- a/toolchain/semantics/testdata/function/definition/order.carbon
+++ b/toolchain/semantics/testdata/function/definition/order.carbon
@@ -5,9 +5,9 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block0},
-// CHECK:STDOUT:   {name: str1, param_refs: block0, body: block0},
-// CHECK:STDOUT:   {name: str2, param_refs: block0, body: block0},
+// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block2},
+// CHECK:STDOUT:   {name: str1, param_refs: block0, body: block3},
+// CHECK:STDOUT:   {name: str2, param_refs: block0, body: block4},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -34,6 +34,12 @@
 // CHECK:STDOUT:     node+1,
 // CHECK:STDOUT:     node+2,
 // CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
 
 fn Foo() {}
diff --git a/toolchain/semantics/testdata/function/definition/params_one.carbon b/toolchain/semantics/testdata/function/definition/params_one.carbon
index c0169825cd08..0ffe39d4df14 100644
--- a/toolchain/semantics/testdata/function/definition/params_one.carbon
+++ b/toolchain/semantics/testdata/function/definition/params_one.carbon
@@ -5,7 +5,7 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block0},
+// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block4},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -37,6 +37,8 @@
 // CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+2,
 // CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
 
 fn Foo(a: i32) {}
diff --git a/toolchain/semantics/testdata/function/definition/params_one_comma.carbon b/toolchain/semantics/testdata/function/definition/params_one_comma.carbon
index d8f40919a478..88071f7e3489 100644
--- a/toolchain/semantics/testdata/function/definition/params_one_comma.carbon
+++ b/toolchain/semantics/testdata/function/definition/params_one_comma.carbon
@@ -5,7 +5,7 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block0},
+// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block4},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -37,6 +37,8 @@
 // CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+2,
 // CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
 
 fn Foo(a: i32,) {}
diff --git a/toolchain/semantics/testdata/function/definition/params_two.carbon b/toolchain/semantics/testdata/function/definition/params_two.carbon
index 0e1b618101e5..fae5404c628e 100644
--- a/toolchain/semantics/testdata/function/definition/params_two.carbon
+++ b/toolchain/semantics/testdata/function/definition/params_two.carbon
@@ -5,7 +5,7 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str2, param_refs: block2, body: block0},
+// CHECK:STDOUT:   {name: str2, param_refs: block2, body: block4},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -43,6 +43,8 @@
 // CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+4,
 // CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
 
 fn Foo(a: i32, b: i32) {}
diff --git a/toolchain/semantics/testdata/function/definition/params_two_comma.carbon b/toolchain/semantics/testdata/function/definition/params_two_comma.carbon
index b508b2d1ddb7..dd8306af9458 100644
--- a/toolchain/semantics/testdata/function/definition/params_two_comma.carbon
+++ b/toolchain/semantics/testdata/function/definition/params_two_comma.carbon
@@ -5,7 +5,7 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str2, param_refs: block2, body: block0},
+// CHECK:STDOUT:   {name: str2, param_refs: block2, body: block4},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -43,6 +43,8 @@
 // CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+4,
 // CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
 
 fn Foo(a: i32, b: i32,) {}
diff --git a/toolchain/semantics/testdata/function/definition/params_zero.carbon b/toolchain/semantics/testdata/function/definition/params_zero.carbon
index b1fe8b956a8b..2d1be58c2a47 100644
--- a/toolchain/semantics/testdata/function/definition/params_zero.carbon
+++ b/toolchain/semantics/testdata/function/definition/params_zero.carbon
@@ -5,7 +5,7 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block0},
+// CHECK:STDOUT:   {name: str0, param_refs: block0, body: block2},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -26,6 +26,8 @@
 // CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+0,
 // CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
 
 fn Foo() {}
diff --git a/toolchain/semantics/testdata/function/definition/same_param_name.carbon b/toolchain/semantics/testdata/function/definition/same_param_name.carbon
index 06ac0f3ae416..63c3d177d347 100644
--- a/toolchain/semantics/testdata/function/definition/same_param_name.carbon
+++ b/toolchain/semantics/testdata/function/definition/same_param_name.carbon
@@ -5,8 +5,8 @@
 // AUTOUPDATE
 // CHECK:STDOUT: cross_reference_irs_size: 1
 // CHECK:STDOUT: functions: [
-// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block0},
-// CHECK:STDOUT:   {name: str2, param_refs: block5, body: block0},
+// CHECK:STDOUT:   {name: str1, param_refs: block2, body: block4},
+// CHECK:STDOUT:   {name: str2, param_refs: block6, body: block7},
 // CHECK:STDOUT: ]
 // CHECK:STDOUT: integer_literals: [
 // CHECK:STDOUT: ]
@@ -44,12 +44,16 @@
 // CHECK:STDOUT:     node+5,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+3,
 // CHECK:STDOUT:     node+4,
 // CHECK:STDOUT:   ],
 // CHECK:STDOUT:   [
 // CHECK:STDOUT:     node+4,
 // CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
 // CHECK:STDOUT: ]
 
 fn Foo(a: i32) {}
diff --git a/toolchain/semantics/testdata/if_expression/basic.carbon b/toolchain/semantics/testdata/if_expression/basic.carbon
new file mode 100644
index 000000000000..ca2c2fe1f11c
--- /dev/null
+++ b/toolchain/semantics/testdata/if_expression/basic.carbon
@@ -0,0 +1,80 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// CHECK:STDOUT: cross_reference_irs_size: 1
+// CHECK:STDOUT: functions: [
+// CHECK:STDOUT:   {name: str3, param_refs: block2, return_type: type1, body: block4},
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: integer_literals: [
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: real_literals: [
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: strings: [
+// CHECK:STDOUT:   b,
+// CHECK:STDOUT:   n,
+// CHECK:STDOUT:   m,
+// CHECK:STDOUT:   F,
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: types: [
+// CHECK:STDOUT:   nodeBoolType,
+// CHECK:STDOUT:   nodeIntegerType,
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: nodes: [
+// CHECK:STDOUT:   {kind: VarStorage, type: type0},
+// CHECK:STDOUT:   {kind: BindName, arg0: str0, arg1: node+0, type: type0},
+// CHECK:STDOUT:   {kind: VarStorage, type: type1},
+// CHECK:STDOUT:   {kind: BindName, arg0: str1, arg1: node+2, type: type1},
+// CHECK:STDOUT:   {kind: VarStorage, type: type1},
+// CHECK:STDOUT:   {kind: BindName, arg0: str2, arg1: node+4, type: type1},
+// CHECK:STDOUT:   {kind: FunctionDeclaration, arg0: function0},
+// CHECK:STDOUT:   {kind: BranchIf, arg0: block6, arg1: node+0},
+// CHECK:STDOUT:   {kind: Branch, arg0: block5},
+// CHECK:STDOUT:   {kind: BinaryOperatorAdd, arg0: node+2, arg1: node+4, type: type1},
+// CHECK:STDOUT:   {kind: BinaryOperatorAdd, arg0: node+4, arg1: node+2, type: type1},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block7, arg1: node+9},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block7, arg1: node+10},
+// CHECK:STDOUT:   {kind: BlockArg, type: type1},
+// CHECK:STDOUT:   {kind: ReturnExpression, arg0: node+13, type: type1},
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: node_blocks: [
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+0,
+// CHECK:STDOUT:     node+1,
+// CHECK:STDOUT:     node+2,
+// CHECK:STDOUT:     node+3,
+// CHECK:STDOUT:     node+4,
+// CHECK:STDOUT:     node+5,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+1,
+// CHECK:STDOUT:     node+3,
+// CHECK:STDOUT:     node+5,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+6,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+7,
+// CHECK:STDOUT:     node+8,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+10,
+// CHECK:STDOUT:     node+12,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+9,
+// CHECK:STDOUT:     node+11,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+13,
+// CHECK:STDOUT:     node+14,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT: ]
+
+fn F(b: bool, n: i32, m: i32) -> i32 {
+  return if b then n + m else m + n;
+}
diff --git a/toolchain/semantics/testdata/if_expression/control_flow.carbon b/toolchain/semantics/testdata/if_expression/control_flow.carbon
new file mode 100644
index 000000000000..deadb0688725
--- /dev/null
+++ b/toolchain/semantics/testdata/if_expression/control_flow.carbon
@@ -0,0 +1,93 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// CHECK:STDOUT: cross_reference_irs_size: 1
+// CHECK:STDOUT: functions: [
+// CHECK:STDOUT:   {name: str0, param_refs: block0, return_type: type0, body: block2},
+// CHECK:STDOUT:   {name: str1, param_refs: block0, return_type: type0, body: block3},
+// CHECK:STDOUT:   {name: str3, param_refs: block5, return_type: type0, body: block6},
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: integer_literals: [
+// CHECK:STDOUT:   1,
+// CHECK:STDOUT:   2,
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: real_literals: [
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: strings: [
+// CHECK:STDOUT:   A,
+// CHECK:STDOUT:   B,
+// CHECK:STDOUT:   b,
+// CHECK:STDOUT:   F,
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: types: [
+// CHECK:STDOUT:   nodeIntegerType,
+// CHECK:STDOUT:   nodeBoolType,
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: nodes: [
+// CHECK:STDOUT:   {kind: FunctionDeclaration, arg0: function0},
+// CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int0, type: type0},
+// CHECK:STDOUT:   {kind: ReturnExpression, arg0: node+1, type: type0},
+// CHECK:STDOUT:   {kind: FunctionDeclaration, arg0: function1},
+// CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int1, type: type0},
+// CHECK:STDOUT:   {kind: ReturnExpression, arg0: node+4, type: type0},
+// CHECK:STDOUT:   {kind: VarStorage, type: type1},
+// CHECK:STDOUT:   {kind: BindName, arg0: str2, arg1: node+6, type: type1},
+// CHECK:STDOUT:   {kind: FunctionDeclaration, arg0: function2},
+// CHECK:STDOUT:   {kind: BranchIf, arg0: block8, arg1: node+6},
+// CHECK:STDOUT:   {kind: Branch, arg0: block7},
+// CHECK:STDOUT:   {kind: Call, arg0: block0, arg1: function0, type: type0},
+// CHECK:STDOUT:   {kind: Call, arg0: block0, arg1: function1, type: type0},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block9, arg1: node+11},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block9, arg1: node+12},
+// CHECK:STDOUT:   {kind: BlockArg, type: type0},
+// CHECK:STDOUT:   {kind: ReturnExpression, arg0: node+15, type: type0},
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: node_blocks: [
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+0,
+// CHECK:STDOUT:     node+3,
+// CHECK:STDOUT:     node+8,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+1,
+// CHECK:STDOUT:     node+2,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+4,
+// CHECK:STDOUT:     node+5,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+6,
+// CHECK:STDOUT:     node+7,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+7,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+9,
+// CHECK:STDOUT:     node+10,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+12,
+// CHECK:STDOUT:     node+14,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+11,
+// CHECK:STDOUT:     node+13,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+15,
+// CHECK:STDOUT:     node+16,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT: ]
+
+fn A() -> i32 { return 1; }
+fn B() -> i32 { return 2; }
+
+fn F(b: bool) -> i32 {
+  return if b then A() else B();
+}
diff --git a/toolchain/semantics/testdata/if_expression/nested.carbon b/toolchain/semantics/testdata/if_expression/nested.carbon
new file mode 100644
index 000000000000..da14e4d65702
--- /dev/null
+++ b/toolchain/semantics/testdata/if_expression/nested.carbon
@@ -0,0 +1,120 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// CHECK:STDOUT: cross_reference_irs_size: 1
+// CHECK:STDOUT: functions: [
+// CHECK:STDOUT:   {name: str3, param_refs: block2, return_type: type1, body: block4},
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: integer_literals: [
+// CHECK:STDOUT:   1,
+// CHECK:STDOUT:   2,
+// CHECK:STDOUT:   3,
+// CHECK:STDOUT:   4,
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: real_literals: [
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: strings: [
+// CHECK:STDOUT:   a,
+// CHECK:STDOUT:   b,
+// CHECK:STDOUT:   c,
+// CHECK:STDOUT:   F,
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: types: [
+// CHECK:STDOUT:   nodeBoolType,
+// CHECK:STDOUT:   nodeIntegerType,
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: nodes: [
+// CHECK:STDOUT:   {kind: VarStorage, type: type0},
+// CHECK:STDOUT:   {kind: BindName, arg0: str0, arg1: node+0, type: type0},
+// CHECK:STDOUT:   {kind: VarStorage, type: type0},
+// CHECK:STDOUT:   {kind: BindName, arg0: str1, arg1: node+2, type: type0},
+// CHECK:STDOUT:   {kind: VarStorage, type: type0},
+// CHECK:STDOUT:   {kind: BindName, arg0: str2, arg1: node+4, type: type0},
+// CHECK:STDOUT:   {kind: FunctionDeclaration, arg0: function0},
+// CHECK:STDOUT:   {kind: BranchIf, arg0: block6, arg1: node+0},
+// CHECK:STDOUT:   {kind: Branch, arg0: block5},
+// CHECK:STDOUT:   {kind: BranchIf, arg0: block8, arg1: node+2},
+// CHECK:STDOUT:   {kind: Branch, arg0: block7},
+// CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int0, type: type1},
+// CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int1, type: type1},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block9, arg1: node+11},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block9, arg1: node+12},
+// CHECK:STDOUT:   {kind: BlockArg, type: type1},
+// CHECK:STDOUT:   {kind: BranchIf, arg0: block11, arg1: node+4},
+// CHECK:STDOUT:   {kind: Branch, arg0: block10},
+// CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int2, type: type1},
+// CHECK:STDOUT:   {kind: IntegerLiteral, arg0: int3, type: type1},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block12, arg1: node+18},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block12, arg1: node+19},
+// CHECK:STDOUT:   {kind: BlockArg, type: type1},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block13, arg1: node+15},
+// CHECK:STDOUT:   {kind: BranchWithArg, arg0: block13, arg1: node+22},
+// CHECK:STDOUT:   {kind: BlockArg, type: type1},
+// CHECK:STDOUT:   {kind: ReturnExpression, arg0: node+25, type: type1},
+// CHECK:STDOUT: ]
+// CHECK:STDOUT: node_blocks: [
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+0,
+// CHECK:STDOUT:     node+1,
+// CHECK:STDOUT:     node+2,
+// CHECK:STDOUT:     node+3,
+// CHECK:STDOUT:     node+4,
+// CHECK:STDOUT:     node+5,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+1,
+// CHECK:STDOUT:     node+3,
+// CHECK:STDOUT:     node+5,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+6,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+7,
+// CHECK:STDOUT:     node+8,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+16,
+// CHECK:STDOUT:     node+17,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+9,
+// CHECK:STDOUT:     node+10,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+12,
+// CHECK:STDOUT:     node+14,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+11,
+// CHECK:STDOUT:     node+13,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+15,
+// CHECK:STDOUT:     node+23,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+19,
+// CHECK:STDOUT:     node+21,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+18,
+// CHECK:STDOUT:     node+20,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+22,
+// CHECK:STDOUT:     node+24,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT:   [
+// CHECK:STDOUT:     node+25,
+// CHECK:STDOUT:     node+26,
+// CHECK:STDOUT:   ],
+// CHECK:STDOUT: ]
+
+fn F(a: bool, b: bool, c: bool) -> i32 {
+  return if a then if b then 1 else 2 else if c then 3 else 4;
+}